I hope you have a witness and/or ploice report for this accident, if not the insurance company will try to screw you outa money thats rightfully yours.

Its definitly his fault, that is...if its documented that he made a moving violation which resulted in the crash, therefor he/she is liable for the damage.

also, you stated you didn't think there's enough damage to call the police and file a report.....any damage, that is visible, even a scratch must be accounted for, and I assume from reading this that, you have some damage. Even a minor dent will cost over a $100 to remove.
I had some idiot back into my other teg, and it left a dent on the rear panel between the tail lites, it was very minor, anyway I took it to the best shop in town, they charged the ins company over $400.00

so like i said, i hope you DID get a police report.