Stayed at the Rila last March and going again on 20th January so it couldn't have been that bad! Yes it's basic, but it's clean and warm, food was ok and if it's not hot enough (Bulgarians don'teat their food hot) there is a microwave for guests to use. 14 of us went and we all thought the hotel was fine.
My Brother was out there last year with his wife and 3 year son, we are both off out there on the 20th Jan and we have ski'ed most places but you can't beat it for value and as mention before.... have fun with the Bulgarians and they are more than nice and hospitable in return.