I have been the last two years and it is much less busy than Disney, but it is pretty busy itself. Saying that, two years ago we did not stay on site and had to wait in the regular lines and they were like a summer day, long, but not unreasonable. We stayed on site this last year which made it a breeze. We went on everything we wanted and went back and forth between the two parks, I highly recommend this.
It made for a fabulous Tday both years!
Disney, on the other hand, is swamped during this time so visit the Wed before if you can or go the Sunday or Monday after. If you go the main Tday days, be prepared for lines.
Jenn