Finally finished Borderlands, the game you'd get if you crossed Halo's well paced FPS gameplay with Diablo's Action RPG compulsion. It works pretty well as a game, here's what I thought after playing through the main story. (Level 36 Soldier, 30 hours).
Moment to moment the combat is very Halo. First person shooter. A recharging shield that forces you to seek cover to recharge (while also pressing the attack to prevent the bad guys from recharging). Limited ammunition requiring some care. Small groups of NPCs with decent squad AI and use of cover. Angular aliens with energy swords. There's a mild innovation in the death penalty (you get 10 seconds once you're dead to kill an enemy and gain a "Second Wind"), but basically the gameplay is Halo.
Except it's an RPG. Your character has a skill tree. You level up, getting stronger as you play. You do quests (er, "missions"). There's a large overworld map you can travel around in, NPCs in towns, shops to buy things in. And loot. So much loot, every Bandit or Skag you shoot is a veritable loot piñata with the familiar white/green/blue/purple/orange loot quality. Same thrill when a new shield drops that's an upgrade or a gun drops that lets you try a new playstyle.
Varying playstyle is one thing I really liked in the game. It works equally well to hang way back with a sniper rifle plinking the bad guys. Or you can rush in close with a shotgun. What style works best varies depending on the map you're on, the types of enemies you face, the types of allies you have (in multiplayer), and whatever guns and skills you've chosen to use at the moment. I changed up the way I played the game five or six times through my playthough, it was nice not being locked into a specific style of play.
It turns out that rushing into groups of bad guys and shooting them in the face with an acid-blasting shotgun is lots of fun. Particularly the gory graphics as they dissolve into a cloud of green goo. I had way more fun than I should have with the elemental damage: setting guys on fire or corroding them with acid is quite satisfying. Weapons have other interesting options, too. Do you want the accurate gun that doesn't do much damage but electrocutes enemies through their shields? Or the wildly inaccurate rocket launcher that shoots six rockets at once setting everything in front of you on fire? Lots of options, even on a single playthrough.
The pacing of the game is pretty good, too. The first 10 or so levels drag a bit and I almost quit playing entirely. But things pick up after a few hours of play: you start getting some character skills that are interesting, you start getting guns that light things on fire, and you start meeting more NPCs and doing more interesting missions. Once past that initial hurdle the game progresses pretty well. You can nose down and just do the main line mission, or go off on side missions if you want a bit more experience or weapons. I never felt the game got tedious, which is rare for me.
The story helps. It's surprisingly well-told given how thin it is. Not to give too much away, but somewhere in the post-apocalyptic wasteland is The Vault, a fabled repository of alien weapons technology. Along the way you meet crazy locals trying to get by, megalomaniacal leaders of towns, goofy robots, and fascist military leaders. The best character is Patricia Tannis, the slightly crazy loner archaeologist. Be sure to do the side missions finding her audio diaries, they're pretty good. The writing's a bit cartoonish, for sure, but the voice acting is great and sells the story.
Borderlands is also really good as a cooperative multiplayer game. Unfortunately I played through mostly solo: I don't really have anyone to play games like this with. But I did play a little split-screen co-op, and one afternoon of multiplayer with a friend that really sold me on the game. Dropping in and out of multiplayer with friends is quite easy on the Xbox, although I gather the PC version is not so good. I don't think the game would play very well with strangers, though, too many opportunities for mischief.
What didn't I like? I'm not a big fan of FPS gameplay, it's a bit stressful for me. I got a bit depressed in yet another blasted wasteland setting, although there is some variety towards the end. While the story is good enough, it's not interactive in any way and nothing particularly memorable. But those are minor quibbles, maybe magnified a bit because I was trying to get this game out of the way before starting Dragon Age. Overall Borderlands is quite a lot of fun, I can definitely recommend it.
Update: I left out one annoyance of the game: level scaling. There's something odd in the game where monsters just two levels above you are nearly unkillable, and monsters two levels below you are trivial. Ie: the level you play (and therefore, the missions and zones) are in a narrow band. It's almost like you do 20% less (or more) damage per level difference or something. It felt a bit artificial and confining.