Uncanny. Hilarious. Frenetic. Can these three words do this game enough justice? No. It's that good.
A defining point of that game was this very class-based system. Because that each class had strengths and weaknesses, it is because of this fact that, given you're playing a normalized match in the game, you and your team will have to work together to bring the enemy to it's knees. While you can shred an entire battalion apart with the HWguy, he's damn slow, so he is vulnerable to the Scout or other fast classes. But why I am regressing into the olden days?
New is the look of the game. Immediately you'll notice that it's got an animated look to it. If you have been living under a rock lately, this is both due to the difficulty of melding a serious level design with character design, and to mimic the look of a Looney Tune's show (in the old days, anyway). If this design throws you off, you'll need to realize that this is one redeeming quality of the game, among many others. Of course, if you don't appreciate it at first, you will after merely a minute of gameplay. The game plays smoothly on any system that could handle Half-Life 2. Just make sure that you toy with settings if you experience hitches or lag.
Team Fortress 2's gameplay is hardly different from the first. There are two game modes available on the few default maps. Over time, Valve has been adding modes to maps which were limited in scope to one only. Anyway, these modes are Point Capture and CTF (the twist here is that the 'flag' object is a briefcase full of papers, which float out of the briefcase when a capturer moves with it). While this may seem too limited, these modes go a lot further than just giving you basic objectives. You can treat either game as a team-deathmatch mode, or melee-only, or what-have-you.
A change from the first game is obviously the trimming of character features, like weapons and such. No one can use grenades, that is, unless you count the Demoman's grenade launcher as such. That's his weapon, anyway, so this doesn't count. While that feature was fun, and worked, in the classic installment, it doesn't need to be present here. It's not missed. To make up for this 'shortcoming', you can pick up ammo for your already devastating main weapons (each class has a support weapon on top, which has around one-third or so of the power of the main weapon) to relinquish your supply and tear apart the opposition. As if the Heavy's "Sasha" wasn't terrifying enough, if he is low on ammo and happens to be near an ammo pickup (or better yet, a dispenser), then he will just get that ammo and get the chaingun whirring again. You also may not like the sound of this, but a Sniper can easily replenish his abnormally devastating (without the splash damage) sniper rifle just as easily as the Heavy's "Sasha." So, while you do not have grenades as a support weapon, you do have ammo pickups for main weapons that are absolutely fun to use, and potentially devastating.
Another feature, which is VERY welcome, which I embrace with lots of passion, is humor. It is very well implemented in the game without ever seeming to be forced. All of the humor comes in the form of your characters and what they say and do. Much of this can be seen just by using the built-in taunt system. It's different for each character and you get one per each weapon/item they have. There is also a voice chat feature which has often hilarious lines being uttered in result as well. Also, the levels themselves may remind you incredibly of the Roadrunner cartoons. The levels themselves have a Western feel to them, and they're often part of factories for super-weapons (like an ICBM, or a giant laser, etc.) or other things. If there's one thing that really helps to keep the game from being frustrating, especially since a match can be INCREDIBLY frenetic from beginning to end, is the fluidity of a level and it's pacing. They're very well considered and are never tedious or halting. There can be some improvements to be made, mostly to build on top of what is already there to impress, but they can come whenever is seen fit.
And, unlike the first game, where your classes were static, only distinguishable by their abilities and uses, you also have actual characters here. The Heavy, for instance, has a Slavic accent and uses lingo from that region, plus he has a personality like that of a gentle giant; he's calm and keeps to himself most of the time, but when the situation arises, he'll lash out and tear everything, and I mean everything, to shreds. The Soldier is a humorous take on the hard-core military types. He's more a Colonel or Major, telling by his throaty voice and use of army lingo. Alas, the Scout is a Brooklyn-type who appears to be a baseball fan. He's fast because, as you can tell from one of his taunts, he gets his extra bit of cardiac exercise. The rest of the characters are just as unique in their own ways. There is a German character, an Australian, a muffled-speech type, an English type (think James Bond), a Southeastern-USA buckaroo, and a drunken Scotsman. Thanks to the characters at play here, you'll come to love your character (many people have a favorite whom they can relate to), and you may also put extra effort into keeping them alive because of their uniqueness. This helps keep TF2 refreshing and exhilarating.
TF2's multiplayer goes great. It is stock full of players who probably have flocked from Counter-Strike: Source, and keeps on coming. It is hard for this game to hog your computer's resources. So, put your money where it will pay off, and get TF2. You'll enjoy it just as much as I did, provided that you really dig the team-based multiplayer FPS genre.