An excellent upgrade to Rainbow Six: Vegas.
A number of additions including new guns, clothes, and armor sit well alongside the sprint button and the offline leveling.
The sprinting and leveling by themselves would probably have made it worth checking out, but the graphics get an upgrade as well, especially in multiplayer.
The single player game tells its story well enough, actually concluding at the end instead of hanging off a cliff. It's even more fun if you played the first one before, to have an idea of what is happening in the first one while you play the second.
The co-op has been immensely improved, and T-Hunt will provide tons of extra value long after you are done, provided you have someone to play with. The maps are generally high quality, although I would have liked to see updated versions of Library, Campus, and Bordertown.
If you liked the first one at all, or any Tom Clancy game for that matter, Vegas 2 will prove to be a fun addition to your collection.