My Feline Mistral 115 is ordered through Broadspeed.I can only provide a partial review as I have not yet taken delivery (expected next week).
Bearing in mind that I ordered in June which was only just when the car came into general release so most of the brokers did not list the 2008 and some that i made contact with couldn't s quote at the time.Broadspeed gave me a good price, at the time it was a bit more than £1500 below list and significantly better than the price I was quoted by my dealer (which was substantially more than list).I decided at the time to go with Broadspeed as they deserved the business in my opinion having come up with the best deal on the first chance (I don't see any reason to buy from somewhere that was willing to rip you off with a high price at the first chance.(I also despise my local dealer which is a Robins and Day dealership). Ironically my car is actually going to come from Robins and Day anyway having ordered through Broadspeed, in this case the car comes from their fleet sales arm, which is how they provide the discounts on this case.
Essentially once Broadspeed make the introduction you pay a deposit and deal directly with the dealer from that point.
The downside is that you are not dealing with a local dealer so you can't hassle them for updates or push for special treatment on servicing or accessories etc (although in my experience dealers don't give you anything special for any loyalty).
They also couldn't give me a decent trade in price for my 207 so I had to sell it privately (which was fine by me but has resulted in me having no car for 6 or more weeks, fortunately I have access to two other cars and a motorbike, so this has not been a huge problem for me.
On the whole I am happy with the service so far but if I was to do it again I would use the Broadspeed price as a target price and would call around all the local(ish) dealers to get their best price.