Yup, this game is awesome BUT it has a steep learning curve. Some people get fed up that there isn't writing on the cards. Believe me, you'll be glad there is very little writing on the cards once you 'get' what it's all about.
Anyway, I agree with the previous poster - the game's best balance was found with the first expansion with the extra cards and including the 'goals'. This is in my view (and lots of other people's too it seems) the best version of the game. The expansions after it, although they do have some interesting cards and ideas in them, just make the game too fiddly and doesn't really add much enjoyment to the game.
Saying that, I am very much looking forward to 'Alien Artifacts' which is another expansion coming out very soon, which takes the base set of cards into a completely new direction.
So, dear people at BGA, please can we have the first expansion for RftG please? After that I don't care