I just finished it, and I must say Mass Effect is the best game I've played in years.
Awesome story line, plot, great adventure with terrific twists.
A few times I even found myself saying "Wow, the character they used for Shepard is awesome!" only to remember that I designed him. They plugged you in so well, and the facial expressions seem better than any other game, even if they do break and glitch. I had one time where my eye lids closed, but my eyes still showed through.
It's a bit disappointing though, I get the feeling that even though the decisions do affect people and the story (You can kill or save some characters, you know?) it will overall end up the same.
I was an Infiltrator, by the time I finished I had Pistols and Snipers maxed out, along with maxed Spectre Training and Infiltrator Training, and mixed other ones. Some Decryption, some Electronics, and others.
I mainly used Garrus and Wrex as soon as I acquired them I switched them out, and had a grudge against Kaidan. He died a lot when I first started, so I switched him soon as I could. The only time I changed this was Noveria, Garrus for Liara because of his dumbass suggestion. I didn't see how Liara helped at all with that situation, my conversation with Benezia seemed normal, nothing special/interesting happened with having Liara there.
If someone can tell me how to use those black box spoiler thingies, that'd be awesome, then I can actually mention something interesting.