Just finished the game.
Excellent as hell. As for the scares, I turned the music off, and turned the effects volume down. Made it much more bearable. I think the game drew from every major space/alien horror in the last 20 years. Hell, even Event Horizon.
Boss battles were decent, pretty straight forward. Nothing mind-numbingly painful. The asteroid shooting was a pain in the ass though.
Looks like I'll do at least 2 more playthroughs, one to do just one gun. Another to finish off kills with certain weapons.
I'll save impossible for last.