I've always preferred Full Tilt over Pokerstars for many reasons. One of the big ones, was when I first started I found the interface confusing, and the tables cluttered and messy. They still are, but as I got used to playing these things become less important to me.
Full Tilt really has done a lot of improvements in 2009. Various updates including the massive conversion to flash. This definitely allowed Full Tilt to be able to expand its features, but in doing so they lost other things including the 3rd party software "Poker Shortcuts" which is a must to multi tabling grinders.