The new wallpaper is definitely an improvement over the modified Lucid wallpaper that everyone really hated. I still feel that Maverick is the perfect release that everyone was dreaming about, fixing all of Lucid's bugs and also stabilizing the release even after the FinalFreeze... definitely the perfect release for sure, having very few bugs compared to Lucid.
The installer is perhaps the most incredible improvement, sporting a partitioning tool that is up to par with Mac OS X's Boot Camp Assistant, essentially using a slider between two large views of your partitions, allowing you to allocate space with one movement of the mouse. This is Maverick's killer feature in my opinion, and certainly makes trying Ubuntu noob-proof.
The Software Center is another killer feature, supporting the purchasing of proprietary software as well as the installation of FOSS. This will be extremely good for companies who don't feel comfortable with publicly available source code and therefore will allow Ubuntu to support more apps than it used to, natively. This is another thing newbies will be perfect with. Even if proprietary software makers can't use the Extras repo, they could still use a restricted PPA to distribute their software and then be able to include it with the Natty Narwhal in the main repository.