I went to Greece last week with 3 children and we rent a BMW X1. Very happy with client servicing: check in was ok at airport but people make a strong case to add insurance policies, adding significant amounts so frankly, for me, this is a bit negative as they try to frighten you so that you take insurance but this is useless in my view (your credit card insures you in most of the cases) . The only snag is how to find the parking when you need to bring back the car, this is the case for all rental companies but it's not easy with no indication at all (except on the right just after motorway entrance), a plan should be a good idea for drivers as if you have a plane, better to schedule 30 minutes to find the parking...
And no surprise on the bill.