Oh, and they're easier to play than the heavier guage. Theyre slacker though. But being smaller also helps the playability, I think.
Theres more pick attack to them - the string grips the pick better than the diaddarios, they carry higher frequencies better, I'm not sure the diameter of the wind has anything to do with pick attack (doubly so since theres plenty of pick attack to plain strings), and they dont have the boominess in the lows overpowering everything that the really big diaddarios did. (but havent lost anything, or very much at least, in low end magnitude, its just less boomy).
One odd thing - the 55 in my newtone sets are narrower than the 48s in my diaddario sets. Dunno whats going on there.