I love this game. I have been a gamer my entire life and I highly recommend Dominion. It has a good combination of things going for it: It's easy to play. Every time you play, it plays differently (thus preventing any "cheap" strategies). It has fairly straightforward but deep rules. It's fun with two players and more. It's competitive but not head-to-head (no seriously hurt feelings). It doesn't require a huge gaming table. It has several expansions that make the game more complex and more fun. It doesn't take 9.5 hours to complete a round.
I would recommend it to both serious gamers and casual players.