It's funny to me how of the two classic Id 2.5D FPS series, the far less important one has been treated much better in the 3D era. The two "modern" Doom games are both reasonably competent but little more. On the other hand, the Wolfenstein series gets the excellent RCTW; Wolf 2009, which I haven't played but was supposedly solid; and Wolf TNO, which, so far, is shaping up to be another excellent Nazi-killing excursion.
Mikey already covered this, but I'll say it again — I don't think I've played another modern AAA FPS that gets moving and shooting this right. You're fast, the guns have punch, kills are brutal. The dual wielding offers some really neat decision making when it comes to gunfighting; guaranteed superior DPS, but only if you're willing to play highly aggressively from close range... love it. It's the perfect encouragement to run up and plug some Nazis from right in their face instead of trying to hang back behind cover. The level design is shockingly strong for a modern FPS; lots of situations with patrolling enemies that can develop organically instead of being heavily scripted. Even the arena fights are surprisingly complex and nuanced. The stealth is... well, it doesn't detract. It's obviously an homage to the original Wolfenstein (the 2D stealth game, not Wolf 3D), and it doesn't generally stick around long before they let you go ham with the guns, so whatev.
Bonus points for some excellent dialog writing — BJ's never-ending statements about how much he loves killing Nazis and blowing their shit up are the perfect reflection of the player's motivation for playing the game. "I love killing Nazis. Shooting Nazis. Stabbing Nazis. Strangling Nazis. Let me kill Nazis, and we'll get along fine. Kill some Nazis, blow up their robots, break their stuff." —these are some of BJ's actual lines from the game. MachineGames knows exactly why you're here, and they're willing to let you indulge in your mass-murder fantasies on socially acceptable targets (the artgame-like marketing that emphasized the game's "serious storytelling" or whatever seems absolutely hilarious in retrospect).