Hmm. I actually can't remember any model that has had a lot of 'malfunctions' and I have been a first adopter for every model since the 1st iPhone.
If anything, it's almost always software that gets updated promptly by Apple if they discover some glitches.
The only thing besides the 4 and 4s antenna issue I remember, was when Apple released a new carrier update so that people's signal strength on ATT(which was the only carrier at the time) would appear stronger. After running field test, the signal was the same, but registered with more 'bars' on the iPhone.
Tricky tricky Apple.