I really enjoy the FPS mechanics as they are really smooth. I am not a huge fan of the grenades. Throwing them feels absolutely useless as an enemy can walk past them relatively quickly. Since you can't "cook" the nades by holding them, you have to basically throw them at your feet and get the AI to chase you over them.... Otherwise... you self-detonate near them, or sneak behind them and plant it on them. Really not how grenades are intended to be used. 
The movement and aim sense are pretty smooth, but the explosives could certainly use some work.