This scenario is very hard and . . . well, that's it. There's nothing wrong with a hard scenario, so long as it is fun enough to keep the player interested despite many deaths and re-tries. A dull scenario is tolerable if you can breeze through it quickly. A dull hard scenario, though, is just no good at all.
Depriving the player of save terminals so that they have to redo a tedious switch hunt when they die - hard? Yes. Fun? Heck no. Fighting Devlins with fists or inadequate ammo - hard? Yes. Fun? Heck no. Frequently teleporting in enemies behind the player - hard? Yes. Fun? Heck no, at least in narrow corridors. (Take a look at TI for teleporting enemies behind the player done right - they are used to block escape routes, not as a "Surprise! Ya dead!" thing.) A vacuum level with inadequate air - hard? Heck yes. Fun? Very much heck no.
There is some good architecture here, and some of the combat is fun - hence the rating of two stars rather than one - but you have to wade through a lot of tedium and "do it again stupid" gameplay to get it.
I look forward to the new version. There is a lot of room for improvement here.