I agree. I thought the game was excellent right up until the very end. With the PC game they could probably come out with an expansion so you could continue the storyline a little and maybe have a satisfying ending, but since this is Xbox that's impossible. Almost seemed like whoever was writing the plot hit a deadline and turned in what they had finished up until that point, just throwing in "Well, this is how I thought it should end" at the very end.
The only thing besides the ending that I was disappointed in was the romances, but that's another topic. Everything else was awesome and made me want to keep playing.