Besides what Jalonso said, I think it's too fast. I know you've mentioned it, but it looks like you just removed the last frames, since everything disappears instantly. If you could only make a smoother transition in the end (and in the other parts, if requirements permit), I think it would be a great improvement!

Thanks Jalonso! I'll be sure to tighten things up on future explosions that I do. 

 The explosion look good overal but you can see that the actual explosion frames are rough and doodle-ish and could benefit from cleaning it up using more delibarate pixel placement.