I love this series. The introduction of Expert times in the third installment was great. I managed to score Expert on all levels in this one, but it took a great deal of replay and strategizing. I come back to this series a few times a year.
This game series is nothing like anything else I've ever played. This installment has been panned in some reviews because of the changes since the last game. I think the changes make it infinitely more fun and more replayable. Beat the game four times in a row already - it's not that short, I just play 15 hours a day, I have no life.