Here's a quote from an article from Wincustomize.com on 10 features that Longhorn needs. This certainly seems to sum up what, in my humble opinion, would really make Longhorn a good Windows OS.
Stop bloating with needless bundling. Every new version of Windows throws in some half-assed imitation of third party software. While we can all appreciate having a "free" version of ZIP or uxtheme or movie maker, it damages third party software development. I'd rather think that when I BUY my copy of Windows that the work was put into features that only the OS vendor could do. Especially since Microsoft rarely puts any effort to let third parties expand on what they bundle (like adding RAR support to the compressed folders for example). There are some features only the OS vendor can really do. I'd rather see resources put there.
It would be so nice to see a new version of Windows that had actually concentrated on making the OS a more secure, stable environment which was a more pleasant experience to use. Let's hope that we don't instead just get the same old stuff with some bits and pieces thrown in to try and put Norton, Mozilla or other innovative companies out of business. Let's have a stable and secure OS instead. What do you think?