I attended two Parties earlier this week ( Sunday and Tuesday night )
Both nights felt busier then the last time i attended, but that was five years ago and a lot has changed since then.
Tuesday actually felt 'busier' to me then Sunday nights party which i found interesting.
Certain Attractions had a very long wait ( POTC ), a couple had longer then expected ( 50min for SDMT & Haunted Mansion ) but as the night wore on the wait times plummeted and things were quite enjoyable.
Many were talk ons at that point (Most Fantasyland Attractions except SDMT ) or had minimal 5 to 15 minute waits ( BTMR, SpaceM, SplashM, etc. )
Character greeting lines were long all evening.
Those never let up from what i saw walking around, but i was not focused on meeting characters while i was there.
Crowds definitely thinned after the first two showings of the 'Boo To You' Parade and the 'Hocus Pocus Spelltacular' stage show.
I recommend staying until the very end...it really is the best time to be there the last three hours of the Party.
Remember, you can use your Party ticket to enter the Park at 4pm and stay to shop on Main Street until 1am.
Have a great time!