I have played with one of the preview releases and I liked it just fine. I just read some good info on Engadget that leads me to believe that I will like Windows 7 just because of the media center upgrades that have been done.
I am excited to hear about media center starting to play nice with DLNA devices and not just Media Extenders. This means that I will be able to use my PS3 to stream music via windows media center and no longer have to use a third party app. Not that I mind using a third party app to do so but I think that everyone needs to get along and talk to each other when it comes to media sharing. I think that most media will be online soon and I think that the more devices that can talk nicely together the better off we will be.
Based on just that I can not wait to get my hands on Windows 7 and get the install complete.