How bad is SeaWorld for New Year’s Eve (or 12/30)?

[mousestruck]

We will be at WDW 12/30 - 1/7 and can’t use our annual passes the first two days of our trip, so we’re thinking about a day at SeaWorld. (We’ve never been there.) I know it would be very busy, but are the crowds miserable? Are there really long waits and wall to wall people like Disney at that time of year, or is it still an enjoyable experience. We’re thinking about 12/30 or even New Year’s Eve. Would love to hear about your experiences.