The following is a translation of the message from Slashdot with my-symbian.com (the original was found). Although the source text is not a complete article, it is worth it. I was in a bit of a hurry, so I will be glad of the corrections sent via private messages.

WP7.5 (Mango) is the second generation of this OS, but still has many limitations, prohibitions and serious problems with usability. This is a list of drawbacks compared to other mobile operating systems on the market. We do not compare special features or abilities, but only those that have become the norm for all smartphones, even for the simplest dialers. Android, Symbian or MeeGo have only a few of the listed drawbacks. The ability of the iPhone to transfer files also has limitations, but they still went far ahead of WP7.5. Even the Nokia N9 with the first generation of MeeGo OS is much better and does not have all these catastrophic problems that prevent the smartphone from being used normally.

OS restrictions

1. There is no real multitasking, applications are “frozen” in the background.
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2. There is no support for Divx / Xvid. Zune converts with loss of quality.

3. No USB carrier mode.

4. No support for micro-SD.

5. Maximum 16Gb of memory per device.

6. There is no file manager. The file system is completely opaque.

7. Zune needed to transfer files. Zune can only transfer photos, videos and music. For regular files, you will have to use the Internet.

8. Your contact information is automatically transferred to the cloud, whether you like it or not.

9. Maximum screen resolution - 800x480.

10. Voice search is bound to Bing.

11. You can not put the MP3 on the call melody, with rare exceptions.

12. There is no VPN support in the "interfine" OS.

13. It is impossible to establish a static IP in the connection, and, therefore, to connect to the ad-hoc network

14. You can not sync with Outlook without syncing with the cloud.

15. Absolutely closed OS, applications ONLY from MS Marketplace.

16. Cannot change font size.

17. It is impossible to rename photos inside the device.

18. In Windows Live ID account you can not change the country after the first installation.

19. There is no centralized notification page.

20. The alarm does not work if the device is turned off. In Symbian / Meego - work.

21. The idle screen is completely empty and cannot display time / notifications.

22. Only photo allowed to put in email-letters.

23. You can not transfer audio to most car audio systems, since the most popular Bluetooth profile rSAP is not supported.

24. There is no encryption support on the client side, which is needed for secure applications like mobile banking and online payment.

25. It is impossible to transfer sound from video to Bluetooth devices, since the A2DP profile is not implemented (!).

26. No Bluetooth support (no HID profile).

27. It is impossible to turn down the sound of a ringtone or alarm by turning the phone over.

28. Strongly limited customization capability.

29. The inability to upgrade to WP8 Apollo.

Usability issues

30. There is no always visible battery level, signal, 2G / 3G / Wi-Fi-Bluetooth status.

31. Task Manager cannot complete applications.

32. The buttons "Back" and "Search" can not be turned off in games or applications, you will touch them and interrupt the work with the application.

33. You need to unlock the device to see how many missed calls and new SMS you have.

34. It is not possible to close minimize a pause application without moving to the main screen.

35. Small fonts in messages are difficult to read for those over 45.

36. You can not create and save playlists on your phone.

37. Playlist can be edited only during playback.

38. You can not search for the music collection in the phone, only in the Marketplace.

39. You can not close the music player, you can only minimize. The widget on the lock screen creates a lot of inconvenience (you can accidentally activate it at an important meeting) and disappears only after a reboot.

40. You can not rewind the current song, you can not see what song from the album is playing.

41. Cannot block automatic orientation change (are people using WP7 only upright?)

42. Online contacts and telephone contacts are mixed and there is no way to separate them (filter).

43. The "Search" button in the dialer leads to the history of calls, and not to the search for contacts.

44. You can not save unfinished SMS as drafts.

45. Call history shows only the type of number. It is impossible to find out how the number is meant if the contact has several numbers of the same type.

46. ​​It is impossible to save or call a subscriber from an SMS message from him.

47. SMS are deleted either one by one or whole threads.

48. You can not select multiple phtographs for deletion, shipment or unloading. You will have to do this one by one.

49. You can not see the properties of the image (resolution, size, date of creation, etc.).

50. Applications are placed in alphabetical order, if you do not remember his application name, you will have to spend time searching for it.

51. The calendar does not have a weekly view, the monthly is not scalable.

52. If you received a letter with an attachment, the phone will download it, there is no schedule that saves you from unwanted downloads.

53. If data transfer and wi-fi are simultaneously turned on, the telephone selection of the channel for transmission is not predictable and usually does not fit the user's habit.

Limitations

54. No live wallpapers, widgets, themes.

55. No vibro-feedback from the keyboard.

56. No svaypa.

57. And flush.

58. And Java.

59. And call records.

60. And call blocking.

61. Forget about screenshots.

62. No automatic wallpaper change.

63. A fully closed OS means that applications cannot interact directly with hardware. Forget about the mass of useful applications.

64. There is no equalizer in the Zune music player.

65. No account of mobile traffic.

66. IE cannot scale text, cannot download files and cannot read pages from the cache.

67. No third-party non-IE based browsers.

69. Up / Down buttons cannot be used for camera zoom (sign of OS immaturity)

69. Unable to open zip / rar archive from attachments in email messages.

70. You can not receive video via MMS.

71. Office Mobile has fewer features than SmartOffice, QuickOffice and Polaris. Shame on you, Microsoft.

72. Google Maps and Bing are not available in most countries outside of the USA.

73. The time stamp of the email message does not show the year.

74. Large differences in the available applications in different countries, users tied to the Marketplace.

75. Not all of Bing’s features are available outside of states, especially Local Scout.

Dumber and Dumber

76. One volume level for all functions including playing music, ringtones, alarms, notifications.

77. Wi-fi is turned off when the screen is off. If the mobile network is available, it will be used instead, with obvious consequences.

78. If you accept a text message while talking on the phone, the beep will stun you with full volume. All other phones reduce it.

79. You can enter only one phone number for one contact, numbers entered in other fields will not receive SMS.

80. You cannot receive / send MMS without including 3G, although MMS does not use 3G.

81. The device cannot be charged while turned off.

82. You need to connect the device to wired charging for wired synchronization.

83. Huge headlines use an important place on the screen and lead to low information density.

84. The device will wake up and show the text of the incoming message, which leads to a violation of privacy.

85. The device can be restarted without entering a security code.

Features even dumber, but which WP7.5 no longer knows how

86. File transfer via Bluetooth is missing.

87. Inability to use USSD codes.

88. The inability to filter the history of missed, received, dialed, recent calls. No calls at all.

89. You can not save or export call history.

90. There is no display of the call duration in the history.

91. You can not edit the MMS-profile to work correctly, you need an application that is not available in the official market.

92. Call history does not group calls from one contact.

93. Call history does not show call time for calls that were not made today.

94. You can not set your sounds for different types of notifications.

95. No sound profiles.

96. There is no silent mode (without vibration and sound) from the menu. To turn on and off you need to go to the settings.

97. You can not accept / send contact as a csv file.

98. You can not save your contacts or SMS to your PC.

99. You can not save a contact on the SIM card.

100. You can not change the sound of the alarm.

101. You can not change the activation period of the alarm.

Additional disadvantages

102. You cannot read long titles in an audio and video playlist, as they are cropped.

103. Zune does not allow the user to add or update podcasts from the device.

104. Zune can only be installed with an internet connection.

105. The alarm plays through the headphones, if they are connected.

106. Forwarded email messages cannot be edited.

107. The volume of notifications in headphones does not decrease.

108. Forcing users to use IE, Bing, SkyDrive, discarding rivals from the Marketplace and hiding the capabilities of the OS from them.

109. Wifi access point mode is not implemented by the OS itself, but is necessary for all WP-smartphones.

110. IE does not have a “Forward” button.

111. Mobile Office cannot edit Office 97-2003 documents. Normal for MS strategy, forcing users to update.

112. Images embedded in email are not downloadable.

113. It is necessary to press Bing cards to announce the direction to rotate.

114. No Silverlight support.

115. Compass gives the wrong direction in the southern hemisphere due to poor API in the OS.

116. Third-party applications do not know how to display notifications on the lock screen.

117. The device does not charge when its battery is completely empty (specific to Lumia).

118. There is no support for lossless audio formats (for example, FLAC or WMA).

119. No HDMI (specific to Limua).

120. There is no data usage monitor (?) Or application allowing this.

121. There is no possibility of updating by air, you need a Windows PC with Zune installed.