I encountered quite a decrease in download speed and got fewer hits when upgrading to 2.3.3.
When I upgraded to 2.4.0, then 2.4.1, and also upgraded the Java engine to 1.4, things improved and it seems to me that my downloads is faster now.
Still, Limewire is trying to connect to 5-6 extra hosts now and then.
The connection attempts disappear after a couple of seconds, but the established connections seems to be quite unstable, and they are renewing themselves after a while.
Other than that, I'm quite happy with the improvements in the GUI using the 1.4 Java engine. (<Enter> now works on OK/Cancel dialogs - yeeah!)
The number of hits on my searches has also somewhat decreased after upgrading to 2.4.x, but that may also be a bug in the Ultrapeer code - several of my connected Ultrapeers is 2.4.x.