Lion:
I've been pretty quiet about it, but Lion is a mess. I'm finding bugs almost daily; some are small, some are real head scratchers how they got thru QA. Perhaps I was spoiled by 10.6 (which wasn't a dramatic update over 10.5), but I guess 10.5 had its problems too. It is just that after nearly 4 years, I don't expect such regressive releases. It has gotten so bad, that I'm not even logging bugs, because I'm so suspicious that some of them are intentional (but unspoken) changes in Apple's OS roadmap.
10.7.1 hasn't fixed things. The fact that it wasn't even seeded to developers, I think, speaks volumes.
Overall, 10.7 is a disappointment. And the regressions are simply not acceptable for the 8th release (10 years in) of a modern OS.
