Their services are inexpensive. Just be sure you have negotiated the rate. Many times I have paid for my trip in the savings of body work that my insurance would't have paid for due to a deductible. I find people in Mexico to be very helpful, almost to the point of being overly helpful. If you said yes to every offer of help you would never get out of the country.
People keep their cars in good shape and clean.
I think that one should carefully study what kind of car they are going to drive into Mexico, especially if you are going to live there for a while. Japanese cars are probably not the ticket due to the lack of parts and knowledge. US cars are fairly easy to find parts for since there are dealers for Ford, GM, Chrysler everywhere. If you have a vehicle that requires difficult parts it might be to your advantage to bring along a spare part of two. Also perhaps a service manual.