UT3 brings back the style of gameplay that UT GOTY had, just its a lot more shiney.
Allthough I like UT 2003/2004 I never found them as fun as the original. UT3 brings back the original game in a new form and also merges 2003/2004 into it with the use of vehicles (including a load of insain new ones).
The GOTY version will allways be my favorite ever since I got it on my 15th birthday (nearly 8 years ago) UT3 is the closest UT game in comparison going by how fun it is to play.
... I will be a UT fanboy till the end!!