we will be returning to the Salem this summer after visiting Tunisia for the first time last year.
you are right that the hotel isn't exactly a palace & it is old but the atmosphere and staff of the hotel more than make up for it. We found it to be very clean and comfortable and the food was fantastic.
We spent very little time either on the beach or around the pool as this fabulous country has so much to offer only seeing the hotel & grounds would have been a waste of 2 weeks.
I suposse it is "in the middle of nowhere" but to us it was the perfect location, 1/2 way between Sousse & PEK and, with taxis outside the gates, you could be in either place in less than 10 minutes for as little as £2!!
The reason we are returning is to see more of the local area that we didnt get around to experiancing last year.