Forestall ran a strict ship when it came to stability and bugs. Ios6 was the most polished iOS version. While I do prefer the IOS7/8 look I do think that there needs to be a very deep clean up update that perhaps optimizes and reduces code base.
Apple is lucky in that they have only <10 models of hardware that's run on a billion devices they should be able to really optimitize performance for each of these devices considering they know what hardware has what power they even designed the damn CPU. An iPhone 4s should still be able to run IOS8 without lag or slowing down to how it does now..
It's not hard to have stability and few bugs when iOS 6 hardly introduced any new features. I still view 2012 as Apple's lost year.