In short, MPL is airline specific. Mostly done in a simulator - you are learning the "specific airline way" from day 1. You get 70-100 hours (depending on the scheme) actually flying. Within the MPL, you also get the Type Rating thrown in because as I said, it is airline specific with that airline's SOPs.
Flybe are the first British Airline to adopt this scheme and I believe they teamed up with FTE and 4 or 6 lucky students have been accepted for this mentored scheme.
Now the biggest disadvantage is that if Flybe suddenly went under (or any airline that has the MPL scheme) you can not just go to another airline. Which is why the Flybe/FTE scheme has a clause that if something goes wrong with the MPL scheme, then FTE will allow the cadets to go straight onto the fATPL course.
Now if everything is fine and you are flying with Flybe on an MPL, then that is great. But if ther airline goes bust or you get made redundant before you reach the magic 1500hrs, then no airline would touch you. Because you do not have a fATPL.
I understand that once you get 1500hrs on an MPL, there is more than just a few CAA forms to fill in to transfer your MPL to a ATPL. I'm happy to be corrected.
Advantage is its cheaper and quicker (12 months and you're in the RHS - again dependant on the scheme).