You can now rate games and write up a review.  Just go the game's profile or board and click "Review".   Select your rating (bad, good, or great) and type what you liked or didn't like about the game.

Your ratings will show up on your played/beat game lists, and you can click the "reviewed" link on a game's page to see all the reviews.

So, played any games lately?  Let us know what you thought!