We've attended three of these events--the very first one at MK, and then in later years, one at MK and one at Epcot. The first MK was truly fabulous with limited capacity, outstanding fireworks, many snack stands around the park (ice cream bars, cookies, drinks) and lots of characters. We found the following years to be MUCH more crowded with very long lines at rides and, with food vouchers only good at a few QS outlets, getting food wasn't worth the wait.
We'll be there for the 5/24 HS; we'll try to register. Just hope they go back to more limited capacity.