About a year ago I retired my aging G4 iBook and moved to a System76 Pangolin Performance laptop. Though I've been using Linux since the mid-90's, I veered more towards Mac OSX around 2005 and mainly used Linux Server with OSX on my desktop and laptop. Last year I went back to Linux, and honest I haven't looked back. The laptop ran 64-bit Ubuntu 9.04, which ran great, but last week I ordered a 1TB USB drive to backup my laptop then ran a clean install of 64-bit Ubuntu 10.04.
My first impression was WOW! Most people said the boot times were impressive, but where 9.04 booted in about 45 seconds, 10.04 boots in under 20 seconds. Also shutdown, suspend, and hibernation work MUCH better under 10.04, which is good to see since early adapters of 10.04 had complaints about this.
As for the interface, I wasn't a huge fan of the stock theme, but after some customization plus using Screenlets I was able to get the desktop looking great, or looks good to me anyway. Here's a screenshot to the left using one of the stock wallpaper images.
I've used Thunderbird with Calendar plugins, but this go around I decided to try Evolution, which I haven't used since since Ximian was bought by Novell. I like it, but I've had to go back to Pan for NNTP since Evolution doesn't appear to support NNTP, or at least not that I've seen anyway. But all and all Evolution syncs rather well to my Google Mail, Calendar, and Contacts.
Though I don't generally post much to Facebook, Twitter, etc, I've setup all these accounts on Gwibber. It's nice, and I may start posting some quick updates in the future using it. I've also setup Skype, Gimp (doesn't come preloaded with 10.04 anymore), plus Flash (blah, have to use Ndiswrapper) and the Restrictive plugins to get support for DVD, MP3, QuickTime, RA, etc.
All and all it's amazing, and well worth upgrading. I read lots of hiccups with Ubuntu 9.10 when it was released, but I think they got lots of problems ironed out with 10.04.