I am not an XBOX fan, but even so I feel this second one makes more mistakes than improves on things from the first one.
It doesn't sound like its going to be fully backward compatible, which is going to either make many decide not to buy it or just make it a little annoying for those who do.
It will allow HDTV quality games, but still uses only a regular DVD media. So with the report that a second version of the XBOX360 will be released with HD-DVD support, some customers may choose to wait on the purchase. (unless they offer free swapping)
I should think they would have a confirmed released date by next month. If not, it would seem to me they don't have a good business plan for the release.
Overall though I think its an improvement over the huge first XBOX. I just don't think things are that well thought out because they wanted to be first out the gates this generation.