My first impression is the same as it was from the alpha: it's great. I love the mechanics, the atmosphere is great, and the graphics are beautiful. Even just exploring is fun, and there's a lot to explore.
I can see how it will get boring after a while, because even with new missions being added you can only go over the same ground so many times. I expect a good number of expansions though, so the lifespan of the game should still be quite good.