I admit I'm a little behind the curve when it comes to console video games, but I have recently been playing Rainbow Six: Vegas, and it really rocks. Having played Gears of War prior to this, I was familiar with the run, duck, and fire from cover game mechanics. What I wasn't expecting was the impressive amount of visceral fun Rainbow Six offers. While chasing terrorists through Mexico and into Vegas, you get to blow up pretty much anything that stands between you and them. Spraying a burst of gunfire through a casino's glass windows while a bad guy hides behind an escalator shouldn't be this much fun, but it is. Heck, sometimes I don't even know where the bad guys are, so I just fire randomly across the room, which is surprisingly rewarding.
The storyline leaves a lot to be desired, but part of my confusion comes from not being able to hear the important conversations before and during missions. I'm not sure if my television is to blame or if the dialogue is rather muted. Regardless, I tend to play games like this using Tuco's philosophy from The Good, the Bad, and the Ugly: "If you're gonna shoot, shoot. Don't talk."
For a generally good time, I can't imagine action games getting much better than Rainbow Six: Vegas. It's easy to pick up and hard to put down.