I beat it on Normal (Hey, Not Too Rough), according to the manual, difficulty. I lost interest in FPSes a long time ago, so I have no desire to try out the higher difficulties.
I had some technical difficulties as it would freeze up, a couple times on Level 13 (of 15). It looks like my 32X didn't like my CDX, so when I moved it to my Model 2 Genesis, it had no issues. All the freezes probably added around 8 hrs to my play time.
I hadn't played this since around when the PC version was released, and had only beaten the shareware Episode 1. I understand this is considered to be one of the worst ports, but I thought it was pretty good. It's been so long since I played it on PC that I couldn't tell you how it compares from a gameplay perspective. I looked up maps of the PC version to have on a separate screen for convenience, and several levels had sections cut out -- I'm guessing the 32X can't handle the larger levels.
The manual is wrong regarding a couple things: You don't get a level clear time vs. par time, and the game doesn't wrap -- if you start on, say, level 13 and play through level 15, it does not go to level 1.
Of the three 32X games I've put in a good amount of time on, this is at the top for me. Other than the inaccuracies in the manual, the only bad thing about the game to me is the pathetic ending.
