Had no problems here it ran smooth, the attacks respond well too, i think what you should be concerned about is FPS preferably with an increased number of enemies in a room, this should be something you will want to test on thoroughly so you know it's limits....
TomFulp
Runs great for me but my machine is pretty good. Is this Stencyl 2.0 or are you on the 3.0 beta?
One thing I noticed... In platformers, sometimes you release and then re-press your jump button before you've quite landed from the previous jump. In these cases it's good to have it register again as a new jump as soon as you hit the platform (if you are still holding the button down and if you had released it since the initial jump). Playing your demo, this seems to happen sometimes but not every time... It results in me running around and not always jumping when I expect to jump.
Hyptosis
Oh, that's a good idea. I hadn't thought of that at all. Thanks! Should be an easy addition.
This is still Stencyl 2, I'm not on the beta. I'm really looking forward to Stencyl 3 though.