Apple is investigating reports that latest iPhone mobile operating system iOS4 causes problems for users of iPhone 3G, after a series of complaints on Apple support forums and technology blogs. Apple is aware of the reports and is looking into the matter, a spokeswoman said.
The most common criticism is "phone is slow after an upgrade". There're also many complaints that "phone drains the battery quickly and becomes excessively hot." Apple's latest iPhone operating system is powerful, and the iPhone 3G is two years old at this point. The new operating system isn't compatible at all with the earliest version of the iPhone — but it's supposed to be compatible with 3G and 3GS, although some features, like multitasking, won't work on 3G.
On Monday, the Mobile Gadgeteer blog on ZDNet said Apple should advise against upgrading the iPhone 3G.