Okay, so this is BioWare's next "epic' RPG following on the heels of its wildly popular Knights of the Old Republic and Jade Empire RPG franchises. The promise of Mass Effect is to deliver a truly epic story that spans the galaxy while immersing the gamer using the "most advanced dialogue system and graphics ever". On both of these counts, I think it has delivered, but the experience is hindered by a few small details, which is what I'll get into first.
First of all: the graphics. Okay, I have to say this is one of the most impressive titles I have seen to date. From the outdoor environments to the character animations, this game, for the most part, looks great. It has its share of issues with lip-synching, which detracts from the dialogue portions at points, but, chances are, you'll be too engrossed in the dialogue (at least the first time through) to care that much. In addition, you will notice some areas where the characters don't look entirely convincing, due to some odd lighting situations and how these interact with the character animation.
In addition, this game does have a lot of pop-in textures, which are a bit annoying, but really only last for about the first 5-10 seconds after the loading screen hits. Sometimes they're not even that noticable, and I have begun to expect this from games, of which even Gears of War, Oblivion, and (rarely) Halo 3 suffer from this ailment, but this is where Mass Effect lost points on sound and visual content.
Another complaint I had with this game is the amount of content you see versus the amount of content you are actually able tgo access. Don't get me wrong, this game is teeming with planets to discover, side quests to complete, and even sub-plots to the main story, but the galaxy is HUGE, and you are only realistically able to visit about 30% of all planets you'll find on the galaxy map. The ones you can't land on are merely just planets you gaze at from the Galaxy Map and glean some information on, and the rest are sometimes too small and too repetetive to actually warrant going back to (most of these are planets you'll land on in the Mako Rover).
Other than these, however, the game is fantastic. One of the best parts of this game is actually leaving you, the gamer, with choices that effect the galaxy and test your moral judgement. At one point in the game, you must choose between saving one of two of your squadmates that are in imminent danger. This portion had me tied up for about five minutes before actually proceeding becuase I naturally didn't want to make this decision. That's only the tip of the icedberg.
The main plot of this may seem cliche: alien race trying to kill all sentient life, but you start releazing many things that make it unique. To begin with, this story isn't about you saving the galaxy: its about you stopping one person that has the potential to destroy the galaxy, even when no one else believes you. In addition, there is a history between the race that wants to kill you and those who came to the galaxy before you. This leaves some interesting possibilities for the sequels (this is only the first instillation in a planned trilogy). I don't want to give away too much here, but I left this game feeling like I had accomplished something and leaving you with a mission for the second game, which I will eagerly be waiting for.
My suggestion: buy this game, play it through once for the story, and then play it through again to get everything out if it you can. I spent a good 18 hours on the main quest alone on the normal difficulty setting my first time through, and I don't want to fathom how long a second time on veteran will take me.