I have an 8 and 11 year old and they still play with our blow up kiddie pool. It's about 6-8 feet in diameter. It's big enough they can even float in one of those circle floaties.

I put it on a tarp in our driveway so we can easily drain it and so we don't kill the grass.

It's definitely worthwhile for us although we only bring it out once every two weeks or so.

We got it at Costco 2 years ago.

Yep, mine are 10, 7 and 3, and we got one, they are just happy to splash around and have something different to do. Tomorrow should be a nice hot day to break it out.

My kids are considerably older, and I just bought one. Even falling into a few inches of water after playing basketball will feel like heaven this summer.

My 4 year old (5 in July) has been using our crappy plastic pool/sand box, and loving it. Now, granted: it keeps his attention for an hour or less, but I'm finding that he and my older kids are also enjoying setting up their own little "beach" in the driveway, and spraying each other with the hose. Normal caveats: extra mud, have to dump the thing often b/c it's filled with tree pollen, more water usage than I would like, but all in all - two thumbs up from me. I suspect they'll only use it more once it gets hotter.

Cons:
Grass is a mess
Emptying it and filling it every night
Will likely turn into a grass and mud pit
“He splashed me”
Can’t leave them for a second

Pros:
Heat relief
Fun...?

^ with a cocktail and a novel.

Too old? I'm 44 (and a half), and on a 90 degree day in summer, I'd sit in a play pool if I had the opportunity.