We prefer Typhoon Lagoon, but we had fun at Blizzard Beach. If you're going during the summer and you don't mind following a 2 yr. old at a water park, then it is worthwhile. We just went to TL again in May, and there is a big area for little ones with slides a 2 yr. old can do. You can take the kids in the lazy river which will give you a bit of a break. I'd put the 2 yr. old in the tube with me, of course.
If, however, you are staying at the Yacht or Beach Club, then it wouldn't be worth it since they have a water park for a pool. It's nothing close to TL or BB, but for that age it would be enough water fun.