Achievement unlocked: Face melted
But to first set the stage a bit, you play as Commander Shepard, humanity's most talented soldier, in a time where Earth has just discovered deep-space travel, joined the galactic communit, and is trying to attain a seat on the Council, a United Nations, like collective that governs the known galaxy. You begin by picking Shepard's gender, appearance, and class. The play creator is nowhere near as deep as say, Tiger Woods', but it's perfectly fine. Now let's talk about graphics, its awesome, sometimes you just have to stop and gape at the game's gorgeous panoramas. The story is fairly long, 30 hours or so, it depends, and Mass Effect never takes the lazy way out of a storytelling moment. As far as pure gameplay goes, Mass Effect is one well-polished action/RPG. It is obvious that no game can get every single thing right, and here's what BioWare screwed up: Item management and squad-equipping in between missions is just obnoxiously complex, and capping the game's save slots at 10 maximum is outrageously stupid. Why can't we fill up out 120GB hard drive with saves? Way more frequent auto-saving wouldn't suck, nor would finding a better button for grenades than the freakin 'Back button. And your squad sure likes to shoot walls, but hey- they're no dumber than your mates in any other game. Still, that's what's remarkable about Mass Effect. If you seperated the gameplay from the story, you could crap on the gameplay for a handful of different things. But in this game, story and gameplay are relentlessly intertwined, and the impact of that is so powerful that any irritation you feel is washed clean away.
Personally, it's one of the best games I've ever played. You have to play it, and that's why I'm kinda jealous of you. Even if you memorized all the previews and trailers, you're not ready for how awesome this game is.