I don't have kids, but I did recently go there with my sister, niece (4) and nephew (8). My nephew was a little old for it, but is generally a good kid, so he tolerated it (I think even secretly liked it). My niece loves it - there are tons of things for her age range. We saw lots of young toddlers (probably 1-2), and I think there are separate sections for them to play in where they won't get knocked around by the older kids...
It's loud & on the day we went very busy, but as long as you can keep track of your kids, you should be fine. They'll definitely run off some steam!
FWIW, my sister did end up buying a membership there (they live about 15 minutes away, so it was worth it for her).
Oh, and I *think* the carousel was built by the same folks that built the one in WDW, but I'm not 100% sure on that.