There are negative reports from users who have updated their iPhones to version 2.2. They say that iPhone 2.2 firmware considerably slows down 3G and even drains the battery by up to 4 times faster(!). Some of them confirmed the first fact by comparing two handsets side-by-side, one of which was running an older firmware version.
We'll wait for the official confirmation on both symptoms. Do you have the same problems?