Very bad.

Cars always exceed expectations, full option, clean great car, very long queue due to bank holiday which is understandable, people at the counter were friendly but of course they have to try to sell insurance, just make sure you know exactly what you want when you get there and you won't get more offers.

The deposit was very high.

Counter staff not very polite, very inconvenient site miles away from T5, Hoppa bus to get to green motion was very expensive.

Allow extra time to pick up your vehicle the office is tiny and busy. I had to wait outside when I first got there as it was jam packed. You when have to walk to the other side of the hotel to collect your car.

Like: We didn't have to wait in line, either for pickup or drop off. The price of the rental was very reasonable. We were given a free upgrade to a larger yet still fuel efficient vehicle, and the car had GPS, which would have cost us substantially more than the total price of the rental if we had to pay for it.
Dislike: Although you can pick up or drop off your car between 06:00 and 22:00 at their Heathrow Airport location, you can only call them (or any other Green Motion office) between 09:00 and 17:00. Also, we had to pay 9 pounds each for my wife and me to ride the Hoppa Bus from Heathrow to Green Motion and back again. While the car rental broker company, EasyRent, said that we would not be reimbursed for this fee, the supplier, Green Motion, said that we would, and we have not yet resolved this issue.