We've had one for 4 years or so. The first 2 years were small, then we picked up a larger deeper pool.
We live in the middle of nowhere, so we don't have a fence around it.
The filters are not real good. I test it often and shock it about once a month in the summer. I have a floater that I put a chlorine tablet in and that keeps the chlorine levels pretty good.
I drain mine every year and refill in the spring. I have a really good well, so I'm able to fill it for nothing each spring, but I have to change the filter every day for the first few days after being filled because of well water.
The water circulates pretty good, but it isn't a pump that cycles so you have to turn it off. If I leave it off for a few days, settlement will settle to the bottom and with these filters, there's no vacuum or anything you can do but to turn the pump on and get in and circulate with your feet to get it off the bottom and moving so the filter will pull it out.
I never have a problem with it getting slimy or dirty, just the settlement on the bottom.
It's really no work at all. We don't have local pools, or anything else local to occupy the kids in the summer, so they are in the pool pretty much daily. It's no big enough to swim, but it does help the kids learn how to float and such. My 9 yr old last year had never been in a real pool, and she was able to swim across the Hippy pool at Pop Century. In fact, the Pop Century pool was the highlight of their Disney trip last year.
I wouldn't be without one for the kids, but they will get older and outgrow it. The oldest, 10 this year, in fact has outgrown it, but we don't want anything bigger with your youngest. I thought of getting something bigger and more of a "real" pool, but don't want to put that kind of money into it. I'd rather go to the beach on vacation than buy a "real" pool, so the cheap Intex pool works for us.