story
Xcode 3/4 were a lot harder to work with (IB and Instruments separate, had to use Clang on command line etc), but I don't recall them being particularly buggy. Xcode 7 with Swift is the buggiest version I have used. It crashes on me 10+ times a day with all of the instant compiler checks it does. The progression from 3 to 7 is amazing, but I feel it has come at the cost of stability.