I am currently undergoing a PPL at Airborne, doing a couple of hours on weekends. I did a bit of research before I started and only negative for Airborne I could find is the prices are not as cheap as could be. Otherwise they have a good well maintained fleet available for training (I'm in a C172 of which there are 5, others available are C152 X 1, Citabria X 1 I think, C182 X 4, Piper Tomahawk PA38 plus other various twins e.t.c.) and they tailor training to your requirements (see below).
My instructor is a young airline bound pilot, but, he is very professional, has all the time in the world for my (sometimes pretty stupid) mistakes and my endless barrage of questions, taking the time to answer them in detail. He challenges me enough so I'm not too overwhelmed but enough to not let me get to complacent and progress in my training. He never makes me feel small for not knowing something or making mistakes, most of the time reassuring me that other people make the same mistake or he in-fact used to make the same mistake when he was learning. If there is one particular mistake I make often he will address it and work with me to resolve it (although my mistakes seem to be very random and all over the place). He understands that although for him flying is about as common as driving a car is to the rest of us, he never forgets that I am in a completely new environment.
At the start of my training, we would do an hour of theory then an hour practicing what I had just learned. It quickly became obvious that because I didn't have time to digest the theory before putting it into practice I wasn't really getting much out of it, so we decided to do the theory for the next lesson at the end of a flight, I was then able to take it home and study it and be ready for the next flight.
Yes it's true they get full on weekends and you need to book lessons about a month in advance, having said that if a lesson is canceled due to weather (which has been happening alot lately) they will usually go out of their way to find extra time for me the following weekend.
Obviously I cannot praise them enough (except for price).