He'll prob 'see' to some while there!
Fair play to him if he does, Sofia is home to some of the most incredible women on earth. And assuming the national uniform hasn't changed in the last ten years they'll all be wearing tiny, tiny black skirts with the legs to make that look work.
I quite liked the place when I was there, and found it pretty easy to get around - although it is a good hike out to CSKA's stadium so you might do better to get a cab. I also found there was a bit of a language barrier outside of the main spots in the city centre, but that may have improved over time, and far more importantly the beer is cheap, the weather should be good and if you can get out into the surrounding countryside it's pretty lovely. Oh, and did I mention the women?