Touted by folks as devolution of the genre due to catering to console monkeys' tastes. Personally, I thought it was a average game that became wildly popular primarily because it was sold to people who didn't have experience with FPSs except crappy ports from the PC that don't really work with controllers.
It's an FPS that played well on consoles. The slower pace, the weapon balance, everything was cleverly designed made the genre viable for millions of players. If the entire point of gaming is "fun" and "entertainment," Halo is a smashing success, and the product of several innovative elements in order to port not just the game but the game type across mediums. Likewise, the best part of Goldeneye wasn't the balance (it wasn't) but the fact that if you're sitting on a couch with three friends, you can screw each other over with glee.
In that stead, what they accomplished is a feat, considering how entire genres simply don't translate. RTSs or, worse, their wargame grandfathers? Pah! G'luck with that. Hell, fighting games! There've always been a few fighting games on the PC, but of all the AAA games I purchased, I regret most of all Street Fighter 4. Why? Oh, plenty of reasons: It's not really meant to be played on a keyboard, its combo scheme is more arcane than most physics textbooks, but most of all, it didn't come packaged with a smelly Chinese teenager waiting for you to put your quarter in. Likewise, you can imagine how Super Smash Bros just isn't right for the PC.
Now, there's still the argument that it made all subsequent FPSs cater to an audience that isn't us PC fanatics, but I don't see it that way. I see games that are console FPSs and games that are PC FPSs, and while the line blurs sometimes, I haven't really lost anything.
Modern Warfare, you could say, was a console FPS in that it held your hand every step of the way, had tiny multiplayer maps and "screw your friends" style win streaks. But I liked Modern Warfare. I didn't like MW2 and onwards, but I didn't buy them and, despite that, I've never really been at a loss for FPSs in the meanwhile. By contrast, I don't see how any console player could get into BF3: The maps are huge, the vehicles require specific playstyles and counters, and the gameplay, while still frenetic, is simply of a different pace than the pick-up-and-play deathmatches in MW3.
Meanwhile, there's still UT3 and, soon, Tribes! Serious Sam and Hard Reset. The world continues ever onward.