My wife bought a Punto there about 18 months ago.

Sales team are fine and the only problem we found was that the spare key wasn't programmed and we couldn't start the car and the AA (Fiat membership) managed to sort it out as a last ditch effort.
At the showroom they made our 2 young sons very welcome whilst all the forms etc were being sorted out. The salesman we dealt with, Russell Palmer, even gave one his bannana! And he gave them a model car each.

Can't speak for the service department as we used Perrys in Amersham for the 1st service as they're much nearer to us. They were expensive but OK.

Generally speaking the service departments of most franchised dealers aren't great. Better to use an independent garage if you can.

My wife is thinking about her trading the car in for her 3rd Punto so the dealership can't be that bad.