MysterD is right.
I think many people saw it at the time as nothing more than a stopgap measure between BG1 & BG2, so didn't get it as they didn't expect it to be very good.
Heck of a mistake - and one that definitely hurt sales of the game.
I actually played PS:T BEFORE BG1 and 2. I wanted PS:T more than BG1 and 2, at that time -- though, I did want to play them. So for X-Mas, PS:T was mine. <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />
After enjoying that one, I moved onto BG1. Eventually, BG2 was next in line, once it got cheaper.
PS:T was really good -- it rivals BG2 & Morrowind, IMHO, as one of the greatest RPG's ever.
