Yes, Descent II OST is on a totally different level compared to the MIDI-only Descent I soundtrack. And by famous musicians to boot - like Type O Negative and Ogre of Skinny Puppy, who created my favorite "Glut" and "Ratzez" tracks. It was the time when games became big enough to bring popular musicians aboard for the soundtrack, Quake with Trent Reznor being a perfect example.

Also, the series was followed by Descent Freespace I/II, leaving a significant impact on the genre of space shooters. Though there are completely different games that have nothing to do with the original series.