I like the new splash screen, very classy. I like the new search filter and the fact that you can change the filters as you want with the little left circle. I also like being able to browse you UP and leaves connections.
The thing that still bothers me is the gui slowdown when you've been running LW for more than a day, the interface becomes very sluggish. I don't know if being an UP as I'm now makes the situation worst.
Congrats, LW 4.0 is shaping to be the best P2P client bar none.