I got it for my son's third birthday party. It was just the right size for him to play in (he's about 32 pounds). At one point we had four kids in it at the same time for a snug fit (a three year old, a 6 year old, a 5 year old and a 13 month old in someone's lap). They couldn't do much but sit in it, of course, and we didn't use the balls that came with it, they were useless - and certainly didn't create a "Ball Pit" in there.

Anyway it says ages 3 and up, but I would think 1-3 yrs old is really the best for this toy. Older/Bigger than that, they're not really interested.