I wouldn't watch it in cinema unless it was femShep. I know that is absolutely ridiculous, but I just don't like male Shepard at all. As far as I'm concerned, when it comes to Mass Effect, he is not the real Commander Shepard. I know I'm one of the 20%, and yes, I am a very dedicated femShepper.
Then again, I wouldn't watch this anyway, at least until it was a bargain DVD, and even then I'd seriously consider just watching it at a friend's house or something. I mean, it's just a phenomenally stupid idea. Taking a game with 40 plus hours of gameplay (if you do all the sidequests, spend a lot of time levelling, explore all the hidden content etc) and then condense it into a 2-3 hour movie?
And what's the way they decide to do this? By not actually using the plot of the game, but making up a new one. Right. That's like making Resident Evil a movie, but putting in a new character solely because the story of the Resident Evil games is... oh wait, they did that, and it sucked. Or like adapting Tomb Raider, but instead of using a story from any of the five games (at the time) or the comics, making up your own completely new one that forces you to rewrite the main character's basest personality and motivatio... oh wait, they already did that, and it sucked. Hard
It does often seem like there's only two options, and both of them are always failures. Rewrite the story so it fits more into a non-interactive medium, in which case the fans hate it because it's nothing like the story they know (see also Final Fantasy: The Spirits Within) or trying to make it very much like the medium the original comes from, which still stumbles over the whole non-interactive thing, which means that the fans don't like it because frankly they already have a good video game to play (See Final Fantasy: Advent Children) and no one else likes it because the only people who get to direct videogame adaptions are usually directors who are just paying their way (see, everything Uwe Boll's ever done)
Seriously, videogame movies are worse than comic book movies, and comic book movies still have Batman and Robin to atone for. (and Barb Wire, and Superman IV, and Scott Pilgrim)