It's a very close adaptation of the table top rules to the computer, and for me it was a dream come true - I always wanted to play Blood Bowl, I think it's one of the best games GW every made, but very rarely had the opportunity. It's pretty much a must-buy for any Blood Bowl fan.
On the other hand, I wouldn't recommend it for the casual gamer without a few caveats:
1. It's a turn-based game, and only really worth playing that way. If you want to play in real time, there are probably lots of more enjoyable games out there.
2. It's a bit of a resource hog, so if you can't live with turning the visuals down a bit, this might not be the game for you.
3. While the gameplay itself is great, the game has some rough edges. While the interface is basically fine, and actual games run smoothly enough, there are a number of things (some of them relatively simple) that could and should have been included to make team management easier, the single-player leagues more interesting, and the multiplayer leagues more manageable.
On the plus side, the developers seem to be actively working on improvements / additions, so there's a good chance some of those rough edges will get fixed.