I just love the 'grenades' in this game, feels so good to use them. Also, the game has an awesome atmosphere.
But this game also has some issues. Mainly the gameplay core: This games doesn't really know whether it's Doom or Super Mario. The jump and run doesn't feel so interesting and got me lost due to issues in the level design. More simplicity in the level design and more focus on just simply delivering a good doom-ish fps experience would serve this game really well in my oppinion (the boss fight *really* delivers, wish the entire game kept me on my feet before like it!)
Still, overall, it's a great indie fps experience!