UI seems similar to mac, who copied whom?
quick boot up
fully customizable, it just feels more open
Ergonomics go down the tubes
--Forget using your multitouch trackpad the way you used to use it on your mac. It's not ready for primetime and may never be. To be fair, most shipping laptops using windows have poor multitouch. I am curious as to why literally only Apple computers have good multitouch. Is it b/c they are the only ones that care? Your palms and other standard ways of typing will cause the cursor to jump around, etc.
--Forget using your command keys. In Natty there is no way to remap them so far, so keyboard ergonomics go down the drain as well
--Poorer battery life. Shave at least an hour off of your previous mac time.
--Backing up your drive a la time machine will not work flawlessly. Odd permissions issues and other unexplained showstoppers.
--launcher and unity interface is a step backwards. Searching for apps is just strange an unnatural in Unity.
--Natty at this point is not nearly as stable as mac snow leopard.
I have spent a solid 3 weeks learning and using linux. The command line is great and I can see the appeal of it, but the negatives right now are outweighing the positive. My basic computing experience has become frustrating. I've spent alot of time adjusting my monitor colors, then having it right and only to have to research how to make the profile "stick" 'at boot up. Having a stable boot loader also was an issue (now solved). This goes to show that mac users who are curious about linux will not be drawn to stay with linux based on its user-friendliness and usability; it will be because of some deep-seated loyalty open-source principles. As I see it, a mac user who is not already well-versed in linux will not be satisifed with ubuntu because the user experience is severely limited at present.