So far I like Spaces, with a couple of caveats:
1. It can be confusing to open multiple windows of the same application in separate spaces. For example, I'd like to have one Textmate window for web development and another for my GTD list, in separate spaces. The problem is that when I use Command-Tab to switch to Textmate, it switches to the most recent Textmate window I used instead of the Textmate window in the current space (which is what I would prefer.) I think Command-Tab should give priority to application windows in the current space. As far as I can tell this is a Spaces characteristic since TextEdit behaves the same.
2. When I open the Find dialog in Textmate, it switches to the last space where I used Find, instead of bringing the Find dialog into the current space. I believe this is a Textmate issue, as it does not occur in TextEdit. If this is scheduled to be fixed in version 2.0, I can wait. Should I submit this as a bug, or is this expected behavior?
Richard