The Colt is a nullity. It looks like zilch and that hardtop weighs. The Micra is possible the ugliest car on the road. The Tigra is a same-as mini convertible; again, just another charmless little open car.
The 500's roof is true to the original, it's comparably light, it offers 90% of the fun of a full convertible with added simplicity, and four proper seats with an ucompromised boot. Pretty clever stuff. Yes, the 500 is more expensive than some similar sized cars, and Fiat can't build enough because it offers what the others don't - charm with practicality.
It's a brilliant effort. If you want a full open sports car get a Mazda, the 500 is different, and for some the additional structural integrity offered by the lack of decapitation is an added bonus, not a disadvantage.
We had three Dyanes with a similar roof system: no leaks, no noise when fully open, no added weight (came as standard), and a real joy to use in good weather, and on those long balmy summer nights when having the stars overhead is a joy.
I don't think some people appreciate just how clever the 500 is to offer practically all the benefits of a full convertible with all the benefits of the standard car left intact. And it looks great too.
No, it isn't cheap, but I'm sure it will sell well, and I can imagine many people just loving it. I do.