The release of Apple's iOS 4 operating system has met with a chorus of disapproval from iPhone users.
IOS 4 is available for the iPhone 4, iPhone 3G, iPhone 3GS and post-2009 iPod touch devices, and adds multi-tasking for the iPhone 4 and 3GS models, plus a claimed 100 new features.
These include a unified email inbox, the new use of folders, which Apple said will make organising applications easier, iBooks, which lets users synchronise e-books across Apple media, and support for Bluetooth keyboards.
However, Twitter users have been quick to criticise the upgrade. One said: "Not happy! Just installed ios4 and it's made my iPhone sooo sluggish and slow it's unbelievable!!"
Another said: "Takes ages to do anything!", while one complained: " Experiencing the horribly slow backup problem with iOS4, been nearly an hour so far."
Apple does include a caveat on its download pages warning that not all new features are compatible with all devices, but it appears that the problems stretch much further than just multi-tasking.
"iOS4 took guts of 3 hours to update iPhone 3G. Waste of time too. Most features for 3GS only. Folders are nice but phone very slow at times," said another Twitter post.
The general theme of the criticism is that the operating system is slow, which flies in the face of Apple's statement that the addition of multi-tasking should let users "run favourite third-party apps and switch between them instantly without slowing down the performance of the foreground app or draining the battery unnecessarily".
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