Outside of combat it's just another RPG. Run here, run there, subquest, subquest, main quest. The running about business was something I hoped Mass Effect would solve, but it didn't. I had to talk to someone, run across town to talk to someone else, then run back again. There is a mass transit system to save some time, but I still covered miles.
Vehicle
I say vehicle not vehicles because there is only one usable one. The Mako, your all terrain armed transport, will remind you very much of it's namesake, the lovable and easily trainable shark. It will most often pick a direction about 45 degrees off where your want to go, and will likely hit something that will cause it to flip, leaving the automatic flippy-agent to take it's sweet time righting you. This six-wheeled, all wheel drive vehicle seems to have about as much horsepower as my 87' Nova, and balks at scaling even the simplest of terrain, and, once said terrain is scaled, enjoys driving itself into oblivion to the craggy rocks below, whereupon it will bounce like an elephant: catastrophically.
Truth be told, it likely won't take any damage from this endeavor, but you probably will be stuck in some inescapable valley like me and have to return to your ship and try again. You will be forced to use this albatross on every undeveloped world, and unfortunately there is an ass-load of them. The only advantages to the Mako are shielding, weapons and speed. It can take a beating, can one-shot most infantry, and on flat ground books it. It is quite satisfying after a nasty trip over a mountain range to atomize some baddies, run over some others. They have a funny habit of sticking to the front bumper, ragdoll effects galore. I particularly enjoyed running down those big four-legged mechs mentioned earlier, as they dwarf the Mako, yet tumble under my mighty treads at the slightest nudge. The Mako is the biggest failing of the game, and although it is only one thing, you use it so much I was glad to get out and walk once in a while.
Plot
Mass Effect has one of the most enjoyable yet sadly predictable plots I've played in quite some time. Thanks to the characters, you really start to root for the home team. Supported by some epic music, I was fairly moved by the sad bitz, and fairly pissed by the nastiness the baddies do so well. By the time I got to the end, I really, really wanted to kill the last boss. I had to make decisions that would actually effect whether or not some of my characters lived or died, and overall I'd say I control the fates of roughly 70+ characters in the game, many major players in the plot. This adds to the replay ability, as my next game, the evil game, will be taking those lives rather than not. I will reveal that the great ending decision is still choosable regardless of your good or evil career, so free reign to you. Your good and evil ratings are separate, and the only effect they have is on your ability to negotiate nicely or aggressively.
Yes, there is alien on human sex in one possibility, even female alien on female human options. There are three romantic options in the game; although I'm pretty sure they left out the male on male option. I didn't look into that option. If you care to, look into Fox News' take on the sex scene for some laughs.
Unneeded Conclusion
Overall, I greatly enjoyed and would recommend Mass Effect to you all. Many will not be able to handle the beefy requirements of the PC version, but most of you should be able to run it in some fashion. The graphics range is pretty wide. The thrice-accused Mako and the routine of Bioware RPGs take away from the fun a bit, but the rest of the game easily makes up for it. Great game, price may be a bit steep right now, but get it eventually, it's well worth the buy, and PC users get a 90+ minute downloadable expansion free, (at some point, they have yet to release it) while the 360Box people have to buy it. (Should it ever come out)
Post forty-hour edit: After one and a half more playthroughs I have found that the dialogue is significantly deeper than I thought. There are many more quests than I thought as well. I stumbled into several quests after exploring some of the less kind dialogues, and particularly when I go evil. The female side has much crappier dialogue, just a weaker voice actor. Plus, I got used to the male voice.
The extra subquests will keep you busy for a while, and I enjoyed trying out the different character combinations, depending on who you had with you different dialogue occurs both between you and them, and each other. During standing around moments my people would ask each other about their background, if they were different races they would ask questions about culture and history differences. All quite enjoyable for someone seeking depth of story.
Replay value is still good, especially for those of us that play once though all good, once all evil. Go forth and buy crappy games no more.