Get the pass (sorry, I forgot the name of the pass), it is worth the extra money. We went during the summer, so naturally it was a busy day. We even got there right when the park opened, and there were already decent size lines at some of the attractions, so we decided to purchase their version of the fast pass. Even though you can only use it on one ride at a time, if you plan correctly, you won't be waiting for more than 5 to 10 minutes for any ride.
The kids really enjoyed the park and the rides because they're exciting but not too extreme for them. For the parents, it's a decent size park, so there's enough to do, but it's not a day long hiking adventure.