I was in MK on Thanksgiving day last year. As I walked into the park, I found myself getting annoyed by people...well...being people. But I reminded myself that most of these people were probably here for the first time and that I needed to be patient. That helped a lot. It was crowded. I had my 3 LL's and I think I got on just a few other things (Philharmagic, the train, and Country Bears) after I used those. I didn't book any more LL's because return times by 10am were into the 8pm time frame. We had lunch scheduled at Diamond Horseshoe at 2:15. We got seated at 3:15pm. We left the park after eating (and shopping a bit). I think I was back in the hotel by 5:30.
So yes, it was crowded. Less than Christmas but still crowded. If you go in with that expectation and a plan, and then remain flexible, its worth it.