ok some first hand experience:

1. usage: in the beginning you use the pool a lot (almost every day) but it slows down until eventually you ask yourself why do i maintain the water. nobody swam this week. of course your mileage might vary

2. maintenance: not so much of a hassle for a small pool such as 4m x 8m. ideally you buy a cover so you can protect the pool from attracting leaves and such.
if chlorine pool: every two/three days have to add in chlorine, monitor water quality blah blah. tideous. if you engage a company they use way to much chlorine to be on the safe side. but in fact they know next to nothing about ph-levels and such. better you handle yourself and get a good testing kit. if properly maintained and pumped you will not have any cleaning issues. if you let it slide you*re in trouble.

if you choose salt water pool it's less hassle ( a friend of mine has one). just fish the leaves if no cover and you're good. but you need special pump that can tahan the salt water. no corrosion issues on nearby metal so i gues no other issues.

3. cost: if you have access to an alternative pool a small pool is not worth the money. for example we found that we much rather go to PJ palms and pay 5 bucks per person. its way larger and you get to keep your garden. also you dont have to bother about maintenance. even if you go to a nearby hotel pool once a week its cheaper. do the maths: 50k for a small pool : forgone interest at 3% = 1500 RM p.a. entrance to a hotel pool around 20 bucks per person (multiply by 4) = 80 bucks. already can go 18 times. then add the maintenance, water and electrictiy cost (easily 100 bucks on top per month) so you end up with 34 trips to a nice pool. thats more than every two weeks.

that of course ignores maintenance costs on the pool wich tips it further down.