Finder does seem a little too picky with network shares, I'll give you that. But they run pretty well if they're set up properly on a good network. It was a source of frustration for me at one point. Finder remembers your last window size, but it doesn't do it in the most intuitive of ways. Another reasonable gripe there.
The stealing focus thing, though, is nonsense. Not only is that one of the most annoying things about Windows in general (for me), but I have no idea how you're managing to do things so clumsy as dump items accidentally into the sidebar.
Finder really is, though, an element of OS X that needs improvement. But what it needs is a radical re-thinking of how it might work. I would disagree with you if you suggested that Windows Explorer is more intuitive. For years I've always been frustrated with the difficulty of traversing the Microsoft OS. One needs to come up with something great.
Spotlight is awesome. Not sure what you're complaining about there. And it absolutely has not gone downhill since its conception. I can definitely think of improvements I would like to see.
No real comment on CoverFlow. It is useful in certain cases, but it is hard to imagine someone using it to browse their OS.
And also, you did comment earlier that 'OS X has many of those problems', or something to that effect. Pulling out a few minor gripes doesn't really set aside your drama, especially when your response was regarding Windows complaints that deal primarily with Windows-specific features.
Finder is simple that was the goal i think and Spotlight is awesome. For example type "Folder" in the Finder search field and you get all folders in that subdir or whole Mac depending how you setup search.