The UI on Maemo is AMAZING. It is outdated and lacking though. It needs voice recognition, spell checking, real support for portrait mode (not hacks), and just a few other tweaks. It is still arguably the best mobile OS ever made by man. However it was killed, the source was not released, it will not be updated, there will be no evolution, and applications will be minimal. If you have a Facebook I can bet you bottom dollar I can get more done with an iPhone 4S/Android 4.0 device on FB than you can using a N900 (I know this to be true because I am the guy with the N900 right now). I wish that was not the case, but it is. There is really no debate the Maemo 5 is by far the best mobile OS out there. But it is outdated and abandoned. I used spell check >10 times while writing this.