I would say if your company is paying stay there. The rooms are comfortable, the bathrooms perfect and the staff polite. It lacks genuine warmth however.
Location wise, it is near the center, but not quite in it. One is thus dependent on taxis to reach nice dinning areas around Vitosha boulevard and others. Their restaurant is trying hard to be an Italian gourmet experience, but it is slightly overpriced, of course.
On the weekend prior to my business days, I booked myself in Scotty's Boutique hotel for 58 Euro a night and had a wonderful stay. Their staff is great and helpful, internet is free, and they are right downtown. It does not offer all the comfort of the Best Western, but I think I would rather go back there.
Booking on Skoosh I saved 11 Euro a night, hats off to them.
Enjoy Sofia.