Do a search on the transporation board... but generally speaking they do not have a good reputation. (check Mousesavers).
We rented from them 3 years ago and would NEVER EVER rent from them again nor would we recommend them to anyone we knew! And it still makes me mad to think about it!!
Here's a VERY BRIEF synopsis of our rental experience with them: Mini-Van promised, then not available at pick-up time. Not only PUSHY about accepting their insurance - very RUDE!! Also added on $$ for misc. services to our final bill. Time wasted for this ordeal over 2 hours in their rental office. Then we fought with their Corp office to have the $$ for 'add ons' credited back to us for 6 months! Had we been by ourselves, my DH and I would have just taken a taxi and picked up a car at National or something.. but there were 7 of us (kids, etc)... so we were tired, cranky, etc.
So my advice - DON'T DO IT! No matter how good of a price they quote you - JUST SAY NO!!!!!!