B.W.
We have the Intex 16x48 metal frame pool and this will be our fourth year putting it up. We've really had so much fun with it! Both our boys learned to swim in it and our daughter will probably this summer too (she's only been home for 3mos so she hasn't been in it yet!)
Just make sure you educate yourself on how to keep the water treated. We do two really good shocks on our water when its fully filled and run the filter for 48hrs straight and nobody in the pool, then we put in the chlorine float and treat for ph, then we shock once every other week. Our water has never turned green and has never had to be drained. Its very easy to upkeep.
If you can spend $500, I would recommend looking into one of the Intex pools with the salt filter. No chemicals and the yare easier to maintain. We also bought a solar cover for ours for $40 because we live in Minnesota and it was hard to keep the water warm overnight sometimes. The solar cover keeps the water warm even in cooler temps (maintains temp) and it gets the water in the high 80's for comfy swimming even on cooler days!