|The Fiat looks more conservative than the Mazda|
Fiat has a poor range of cars in my opinion. It doesn't have a lot of money to play with either as much of that is going to revive Alfa Romeo. It needs more models and it has landed one courtesy of Mazda, the Fiat Spyder. It was going to be an Alfa model but the decision was made for it to be a Fiat, including a sportier Abarth version later as well.
The original Fiat 124 Sport Spider was a 2+2 convertible sports car made from 1966 to 1985, with some 150,000 made over 20 years (that's 7,500 per year). Emulating that again will be a challenge but either way the new one will create interest, profile and some profit.
The design done for the Fiat variant cannot hide the donor vehicle, but it does look sufficiently different. The Italian car will have a 1.4 turbo petrol, with less horsepower than the Japanese equivalent but more torque. The Fiat will go on sales from about the middle of 2016 on.
I like the idea of such collaborations. It is cost effective and I presume it will raise the profile and sales of the car with two makes selling them. I guess the Fiat will sell mainly in Europe with some in Latin America, while Mazda will rely on Asia and North America. In that sense, it should be good for both.