BioWare hasn't given the player the option to map their own face onto their character, but this is because the complexity of the normal maps used for the faces wouldn't allow for it. Personally I'd rather have the faces looking as realistic as possible, rather than overlaying some dodgy photo map of my face onto my character, so well done to BioWare for offering the best possible visual experience over a cheap gimmick. It's also good to see that absolutely all the cut scenes and animations use the in-game engine - nothing is pre-rendered in Mass Effect.
But it's not just how Shepherd looks that matters, it's also what he can do. There are six classes for you to choose from Soldier, Engineer, Adept, Infiltrator, Sentinel ad Vanguard. The soldier is obviously a battle hardened warrior who's very proficient with an array of weapons. The Engineer is skilled with all things electrical and mechanical, and the Adept is skilled in psychic powers. It's the next three classes that are the most interesting though, since they combine the other three. The Infiltrator is a cross between the Soldier and Engineer, the Sentinel marries the Adept and Engineer, while the Vanguard combines the Soldier and Adept - it's the latter that I went for when I played the game.
One of the most important things about Mass Effect is that it's as much of an RPG as you want it to be. This game could very nearly be described as an over-the-shoulder, third person shooter, if that's the way you decide to play it. The basic combat is very slick and definitely doesn't feel anything like kind of laborious combat systems that are often associated with role playing games.
If you want to get the best out of the game though, you'll need to use everyone in your party to the best of their abilities. The good news is that BioWare has made this very simple indeed, and it really does only take a few minutes to get to grips with the full combat system. During combat holding the right shoulder button brings up a list of all the Psi attacks that each member of your team has at their disposal. From here you simply assign each specific attack to the desired targets and release the shoulder button. The left shoulder button brings up an almost identical menu, but this time for traditional weapons - obviously for Shepherd you're firing his weapon in real time during combat.