I came across the same sorts of issues as others, also dying on the end battle. I feel that could have been improved if I'd known what to expect more.
Maybe a short button hunt to activate things beforehand.
Demo, where I complain about people bugging me while trying to play;
https://www.dropbox.com/s/cfxizyyqdqqznkk/ijedmfx17.zip
Some encounters felt a bit forced. Sentinels are a great enemy and were well used, but the Pyro and Plasma troopers feel oddly balanced and it seems you didn't place them as well as other enemies because of this.
The Chicken Centaur (Edie) was fun as always. I thought the end battle could have been better with them than the shamblers actually, since the compact areas would have left the player herded up against them and their buzzsaws, while not having cover to avoid attacks wouldn't have mattered as much without the hitscan shambler lightning.
Oh, and I got lost after finding the lightning gun secret. The shortcut turned out to be the long way round :)