The deals are good, but at the end of the contract, they will look for any and every fault scartch mark or nick on the car as a way of lowering the value of it as much as possible. The idea of PCP, is that you'll hand the car back as part exchange on the next car(new or used), and so coninue paying another set of rental payments ad infinitum. PCH is personal car hire, and it's renatal scheme whereby you give the car back at the end of the hire period, so it's similar to PCP in that you'll always pay for a new car, (and have the same, what can we catch you out on routine) but the payments are lower than PCP as you have no personal investment in the vehicle.
PCP will be the new PPI scandal soon, so avoid it like the plauge.