Firstly, just to clear it up, Uber and their drivers are regulated in exactly the same way as any minicab office in London. All drivers have been registered with the PCO since 2003 and have the same CRB checks etc. as black cab drivers (though I don't know what they stop them driving for, presumably rape and sexual assault but I've seen some shocking CRBs on licensed drivers over the years, including violent crimes). TFL also insist that Uber have a bricks and mortar office in London with a PCO license on the wall and keep detailed files on all their drivers.
From most drivers' point of view it's been a godsend. They can work when they want and no controllers screaming at them or bullying them into 15 hour days. They seem to be making a better living out of it than they were with the other firms too. However, those of us who hoped it would affect a certain London major player's stranglehold on the industry have been rather disappointed as it's affected the smaller players a lot more, some of whom have gone out of business and some of whom have been bought out. Driver wages have been pretty much frozen (and indeed gone down) since 2008, Uber have managed to get a lot of them making more, not by having better rates but by giving them more work and less dead mileage. If we end up with two big players locked in a price war it's not going to do much for their wages in future.
Ultimately the only thing that's going to help minicab drivers is if they do what the black cabdrivers have done and unionise. Until then they're at the mercy of market forces and while it may give them a little uplift sometimes, such as this year when Uber needed to get a lot of drivers on their fleet quickly it's not going to work in their long term interests.