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
The properties you may filter on are right in Explorer.
Any of the metadata names can be used as search filters. You can use the column dropdown controls to filter without having to remember the term to type. You can also right-click on the column header, then click More... to see all properties supported by that version of Explorer (or check the file properties dialog for metadata specific to that type of file). If a property name is composed of multiple words like Date Taken, remove the space, so you would type datetaken: in the search box.