I, like several others, got the game for Christmas. It's quite a blast. The scope of some of the areas like the Soviet Installation is very impressive (even if I must have missed a map there, damn you!), the tombs are more interesting than in the original and I prefer the variety in the setting.
Currently at the geothermal Valley, yeah its a bit of slow progress but I'm enjoying going around collecting everything and doing all the side missions, and doing that whilst keeping your interest for me is the mark of a quality game.
For that price you'd be a fool not to get it. For those without an X1, definitely look it up next year!