Like the first, except around twice as better. I love the new additions to the cannon types (the machine gun one had to be my favorite of them all), but what I loved most was the way you seemed to abide to the old saying, "If it ain't broke, don't fix it,", because sometimes Flash artists tend to try and go a different direction in their sequels, which can either make or break a game.
But yeah, this game is much better than the first, and I love the concept of it. Plus, the graphics look great, even for a Flash game! The only thing that I noticed while I was playing (which is not so much a glitch as just a slight quip), was the fact all the shots go through the platform Max is on. I don't know if it would make it more realistic if the shots collided with the platform, the cannon, and Max itself, but it's just a note.
Anyways, great job on this, man. I know I won't be the only person waiting for another sequel!