Warning: I'm about to go on an old person rant 
Oh, I see what you mean! That might not fit with the Duke Nukem character, though. Duke Nukem is a game character from the 90s, most famous for Duke Nukem 3D (1996) which was a very popular early FPS.
Those games, unlike slower-paced modern games, were usually about running around at impossibly fast speeds, blowing up aliens as you go without stopping except to say cheezy one-liners. I feel like Duke wouldn't know how to be slow!
Probably more information that you were bargaining for, but if by any chance you are interested, try checking out the EDuke32 source port or the Duke Nukem 3D 20th anniversary edition on Steam.
It's completely up to you, but I think it's just too fast. The individual frames are fine, I can focus on each pixel for long enough to tell what's happening ^-^ -- the pixel art just has a spy-feel to it, and I think it should have a smoother and more relaxing feel to it (think of every action movie where the protagonist walks away from the explosion in slow-motion). Hope this helps! 
Thanks! Slower because it looks to fast or slower to see what's happening in the individual frames?
Really cool animation! Would it be possible to make it slower? .3.
Thank you! I just edited it to have even more going on in the animation.
There is so much going on in such a small space, this is what makes pixel art so cool! :D
So many great one-liners in the build-engine games. I'll have to do Caleb from Blood some time...