I have one, OP, which I bought in November after wanting one for ages. I'm over 50 so to the PP who said she was too old at 37 - you're really not! Previously I had a Fiat Punto which lasted me almost 10 years and did 170,000 miles. It was a good reliable car but never had the wow factor of the 500.
What sold me on getting another Fiat was when someone ploughed into me at a roundabout. His car was completely smashed in at the front but my Fiat punto had barely a mark on it. I decided then I would replace with another Fiat.
I love my 500, absolutely love it. I have a 2013 model, not that new, low mileage. It's pretty nippy and I've done some reasonableness distances in it (100 mile round trips) and found it fine. I bought it as a car just for me though, because my DDs are now grown up and driving themselves, so I don't need to fit 4 people in any more. It's a bit cramped in the back!
The only downside? You've seen it already on this thread. There's something about them that brings the misogynistic arseholes out to play. I noticed it as soon as I drove it out of the showroom. People treat me appallingly, cut in front of me, push, overtake, make hand gestures etc. Before posters say it's my driving, we also own an ancient Peugeot 406, 17 feet long, towbar, built like a tank and I never, ever get this kind of behaviour when I drive that.
Within a month of owning it, all the glass was vandalised whilst I was in the supermarket. Supermarket and police were less than interested, I got the windows fixed on insurance. Except autoglass came out and made the crappiest ever job, wrecked the car, the glass doesn't fit, and I'm now having to escalate and battle that. I get the feeling they take one look at it and me and think "silly little woman in her girly car" and you CANNOT get taken seriously. It's seen as fair game for a joke, which reflects society's still appallingly sexist attitudes.
I since found out it's the most vandalised car by a long shot. I now park by other Fiat 500s and I notice they do the same to me! It can make you feel a bit vulnerable so that's the only downside you might want to consider for your DD.
Hope this is of some help!