I wouldn't call descents controls straightforward regardless of what mod/engine you use. 6 AOF Games are hard to play and descent is quite a hard game even in easier difficulties. That being said, it's a lot of fun for sure.
Descent has some limits on how fast you can adjust pitch which can be odd for new players (some of the ports can turn those off, but purists may object)
Takes a little getting used to, but is pretty intuitive, and gives nice smooth analogue axis for all 6DOF.
Edit: and Freespace!