We had one for years, we loved it but have replaced it with a fiat Doblo 1.6 diesel, cheaper and (a little) more economical. Its not easy to find lowish mileage Multipla's for sale and I think they have ceased production of new ones this year. the doblo has a huge boot and three full size seats in the back. Other "van" type cars like berlingo's and kangoos also fit three car seats and are good value.
i have one, i love it but i have had a few problems with it, mainly the electronics. the fact that i mainly do town driving means that the engine doesn't often do high speeds and the engine warning light keeps coming on. it needs to go at 60mph for 20 min to do a full engine check via the on board computer, if it can't do one the light comes on, drives me batty. that said i like the car, i can get the 3dc in the back and the pram and a weeks shop in the boot. we took ours camping in france in the summer and got the whole lot in the boot.
We have one of the older "bug" style multiples and love it, we have 4 dd's under 10 so have 3 car seats plus another child and there is plenty of room. We like how all of the seats are full size with 3 point seatbelts, they also move forward and backwards and can be folded or removed completely. Ours is a diesel and is very economical.
I had the diesel version, we've just replaced it as it was getting on, but this summer we drove from here (West Wales) to the Alps, into Italy and down to the Med then across to France and back home, over three weeks. With three children and two tents . The car did us proud and I notice now I have a different car I get through a lot more diesel (although that may be down to my 2l turbo engine!)
It's not a glamorous car and the boot isn't huge nor is it the drive of your life but if you have three DC's and want a car that will fit them all and the shopping (and two tents and all your camping equipment - we took a seat out) then it does the job. Not really selling it am I, it's a lovely car, fits the kids and can drive up here loaded until it bursts without complaining, can't say more than that.
A friend had one, a car crashed into whilst it was parked outside their house and it was written off. She was beyond gutted, it was her perfect car. We have a Honda FRV which has 6 proper seats and a big boot. More £ tho.
My Multipla died at 110k, the gear box went, too expensive to fix.
I don't think FIATS are any worse than any other car these days, Volvo's used to go on forever but i know several people with unreliable Volvos. The experts say that if you want major reliability you have to go Japanese. Honda FRV's are much more cramped than Multiplas and are also hard to come by. (I did loads of research when our Multipla was getting elderly.)
I learned to drive in our Multipla, I still get a pang when a "bug" style one drives past.
I can't remember who told me they were stopping making them, probably someone who was trying to sell me a different car!
Definitely avoid a new diesel (of any make)as they all have particulate filters fitted now which leads to the engine warning light problem as mentioned above if you tend to drive mainly short distances at slow speed eg. school runs.
We would have bought another Multipla if we could have found a lowish mileage secondhand one in Scotland before ours died but it died when we were on holiday so we had to get what was available at the time!