It's a brilliant game, and you'll really see how much U2 improved on the gameplay if you play it. The controls are a little loser and the cover system isn't as fluid as in U2. However, the melee combat is better than U2.
Storywise, each game is completely standalone. U2 has a few references to U1, they are very subtle and only players of the first game would spot them, otherwise you would not even notice them to wonder what it is referencing.
If it didn't have a "2" on the box, you'd be forgiven if you didn't know it was actually a sequel. Anyway i recomend you get the game just because it's brilliant.
