Yes, it's great to use, especially when you can stack referral/promo codes. I loved having the A4 to drive, it's a great step above the regular rental car offerings and the Google Maps GPS/wifi was handy to have if you don't have a US data plan for your phone. I was in Texas, and ripping along at 80+ MPH was rock solid on the toll roads. Plus, hotel valets tend to give you better service when you pull up in an Audi.
Driving an A4 around beats a Toyota Camry any day. It's a great driving experience and if you find some twisty back roads all the better (they tend to be S-line models with the bigger wheels/low profile tires).
If you can, please use my referral code of 'DTAN' and we both get $25 in credit.