NOTE: READ FOLLOW-UP POST
I've played about an hour or two of this so far and I'm liking what I've seen (okay, I'm grinning like an idiot). This is an old school point and click adventure game. The art captures the characters look and feel really well, plus the voice acting is spot on for Doc (Christopher Lloyd again) and Marty (dude who you would SWEAR is Michael J. Fox). Plus Bob Gale (the guy who wrote the movies) worked on this game as well. Warning, the game is episodic, meaning you will only get part one of five this month, and will have to wait about a month per episode.
Basically, it boils down to this: If you're a sucker for nostalgia and liked the Back to the Future movies, you'll like this game. If you like adventure games like Grim Fandango and you liked the Back to the Future movies, you'll like this game. For anyone else, I can only suggest they check the game out (videos, demos if there are any, etc.).
You can get this game via the PS3's PlayStation Network, or via Steam for PC/Mac users. Surprisingly, XBox Live got left out of this one.
http://www.telltalegames.com/bttf