Judging by the UI of the preview version I tested, it appears that part of Novell's master plan involves borrowing heavily from Apple. From the first boot of the installation CD to the first true boot of an installed server, it's clear that the layout and design of the GUI takes a page from Mac OS X, and does it well.
Swooping visuals aside, there are lots of changes behind the scenes. The installer is still based on YaST (Yet Another Setup Tool), but its appearance and function are more fluid, and the initial hardware detection code has been improved, making the GUI installer available on more hardware combinations.
Several default installation choices have been changed as well, not the least of which is that the default desktop choice is now Gnome rather than KDE. Novell's acquisition of Ximian and the Ximian Desktop has finally pushed KDE to the side, which is sure to be a point of contention among hard-line Suse users. A fully configured firewall is also now a default, which wasn't the case with SLES 9.
Installation revealed a much improved package management system and an online update mechanism that is less apt to throw up a flurry of bizarre dependency problems -- and usually fail to handle any updates at all without help. I did run into some unexplained errors during a vanilla installation of SLES 10, specifically with the YaST2 autocloning feature, but that might be due to the prerelease nature of the code. Another interesting back-end change is the deprecation of JFS (journaling filesystem) for ReiserFS 3. Novell claims that this will be the last release of SLES to support JFS by default.
SLES 10 is plastered with Novell's touch. It ships with Novell AppArmor, which is Novell's reaction to Red Hat Enterprise SELinux. AppArmor and SELinux function in similar ways; they provide a system watchdog that is configured with known boundaries around individual applications and services, such as Apache and Samba, and will prevent these applications from treading outside their known safe space. This greatly reduces the risk of individual application exploits from interfering with the operating system at large.