I see one thing that seems a bit worrying. If the testing garage fails the vehicle, it has to be put right there. You cannot drive it to a garage of your choice as this will involve a heavy fine. The opportunity for a bit of money making from a dodgy garage will probably prove irresistible.
Although they have made a big song and dance about it, this is the same as the previous MOT, if the vehicle was classed as dangerous in the MOT, you were not allowed to drive it. In any case if the vehicle is dangerous you weren't even allowed to drive it TO an MOT.
The difference now is that the police number plate recognition system can identify this MOT status so you are more likely to get caught if you are driving a vehicle classified as dangerous.
Most of the items in the new MOT Manual (still draft when I read it a few days ago) that permitted it to be declared dangerous are pretty serious things, there are many failures that aren't classed as dangerous.