If I can't get it in the repository, I install from source. It takes longer, but I may as well.
As for UI, I wish you could have at least three different GUIs. The "classic" and its themes, something "Mac-ish" and the Spartan Special.
Most importantly, I want to see an icon box. Xfce has one, I thing OSX does (I know the OSX-like dock I use does), and Aston (for XP) makes one that comes with its virtual desktop thing. I'm much better at picking out pictures then I am hunting for text on a task bar. Get rid of the text and make the icon larger.
What do you mean by icon box? The area that windows are minimized to? If so, then yes the OS X dock features that. Windows are minimized to icon form to the rightmost side of the dock, between your documents/folders and the trash.
The learning curve isn't too bad for ubuntu now. I actually like the way it is. You have to learn a little bit, but it's set up in a way where it's not too hard and you actually begin to understand at a deeper level how your OS works. (windows is more of a it works, it works. OSX is more, it works, just use it)
I agree about ubuntu, but I wouldn't be so sure about OS X. It might just be because I'm an inquisitive type when it comes to OSes, but I learned so damn much in the course of using OS X.
Before OS X came out, I used Mac OS 9 like every other Mac user out there. I knew how to use it well, and I could mod its system files with ease, but when it came to using any other OS I was pretty dumb. Commandlines of any type, for example, were a huge, frightening void.
Then OS X 10.0 comes out. It's slow, doesn't have many apps for it yet, and is still buggy, but damn it looks a lot nicer than OS 9 did. It could also run more than one or two apps at once without crashing (unlike OS 9) - "what a revolution!" I thought to myself. Because of that, I stuck with OS X despite the bugs and reduced speed.
Since then, I have poked around in the internals of the OS many, many times and have become very familiar with the commandline. In fact, many of my daily tasks, such as uploading stuff to my web host via FTP and torrenting, are done completely with the Terminal. I'm starting to lean towards it for file management too, since it's at times faster than using the Finder or any other UI. OS X also acquainted me with a lot of terms that OS 9 just didn't bother with.
So yeah, it actually taught me a lot.