We've been a few times years back. It has really been getting busier with each passing year. So much so, I beleive you'll find that it is no longer a "value" weekend. It seems folks add a day (either the Tuesday after or the Friday before) and those days are heavy.
Also, the last time we went, the temps were in the 40s at night. The Luau at the Poly was cancelled and we ended up having to buy some heavy sweatshirts! So pack accordingly. Have some light knit caps and some of those small strechy gloves in your backpack to pull on during the nightly parades, etc.
Have fun!