and Quake 2 wasn't much better, but this is the nature of the beast, as it is an ending to, (a good game as you probably wouldn't have played it to the end if not), and as such the end will usually be disappointing.
Half-life was disapponiting, I thought TR2 was ok and Unreal, but how can you make an "ending" much better if you need to leave it open for a part, two, three, four or whatever depending on sales of the one you have played?