Onslaught is very fun to play, it requires a lot of team coordination. The vehicles aren't weaks like the ones in XMP (3 emp nades = boom), so that means theres actual stategic importance in using them.
I loved assault and am glad that Digital Extreme brought it back into the UT series. The atmospheric feel of AS-Convoy is refeshing, the feeling that you're speeding through a desert canyon is well conveyed. This map reminds me a lot of AS-HighSpeed( Assualt level taking place on a train) from UT, but a lot less linear.
I'm definitely preordering the UT 2004 DVD-ROM, plus I'll be saving $20.00 because I purchased UT2003 a year before.
UT2k4 > UT2k3