We started out years ago with one of those 10x6 foot rectangular blow up pools...graduated to the 12' foot Intex, then the 14'. We only ditched the 12 footer because we had a leak in the donut ring that we couldn't be bothered to find, and the prices on them were dropping rapidly at that point. We used our 14' Intex for a couple years with great results. It came with a slightly better pump/filter that always worked well, and I figured out how to rig a more 'real' vacuum with some left over hose and the return basket cover. I'd say it was well worth what we paid for it, but my kids just outgrew it. It's a great way to learn how to deal with pool chemistry while having a great place to splash around.

I will say though that our site wasn't perfectly level and our pool did take on a more oval shape as a result. Because of that I tended not to keep it at full fill level, so I didn't overtax the walls. It never did fail though.