One thing that I don't like about the search in 7 is that you need to know all these words, like for example "kind". I would have never guessed that "kind:picture" works after all. It's hard to discover, in my eyes. It's powerful, that's for sure, but still hard to discover.
It would be nice to have a UI that gives me all these keywords so that I could build (by clicking on checkboxes, or something similar) the queries. And I mean all keywords and not just some of them, like the current drop down does...
Other than that I'm really happy with the search that's included in 7. It's fast, seems to use less resources and I quite never use dir /s again
But we have that UI. When you click in the search box, it suggests filters like "artist" (for the music library) or "type" and so on. If you make the search box bigger, you'll see more of them.
If you want to learn others, there are documents online describing all of them.