No experience of them .. but looking at the prices they're charging I'd have a look at the train
Bologna station is a very short ( ~€15 / ~10 min) taxi from the airport ... trains to Florence are very frequent and the high speed ones take less than 30 mins to the station in central Florence
Driving from Bologna to Florence is on a fairly old windy twisty motorway through the mountains and the traffic can be very bad sometimes ... even without traffic it's definitely slower than the train.