I use Greg's car's about every two months and have never had a problem and they have saved me a fortune over the years compared to the airport car rentals that I used to use previously and are certainly not rip off merchants.
They are legal and reliable but older cars, which is why they are cheaper but no cons such as extra insurance needed or bring the car back empty or full etc. They also provide childrens seats free of charge if needed and the biggest bonus is that they pick you up from the airport and drop you off so no stress before or after your flight which is perfect if you are unsure about directions, have an early flight, or want to have a drink on the flight over.
As they are also a business started on Condado I also like to support them and Greg and the people who work for him are lovely but they may be fully booked so don't leave it too late to enquire.
Bee