You should add a feature where you can upload custom textures from like jpg, png, ect. instead of just changing the color of stuff like "Gray1" Wouldn't it be cool if instead of a traditional grey you could have your guns look metallic?
Adding too much blur and a different combination of layering effects will save the picture with transparent blurs around the skin, so when you put it on in Minecraft, it renders those blurs as hat layers and leaves you with a hat around your bottom right front head and side head that you do not want. If this glitch occurs, open the file in paint (Or any other conventional picture editor) and trim off any of the extra blur around the skin.
I like the fluid animations and the loads of partical like effects. Though the game can be frustrating at times, I believe this game is well worth a 5/5.
I'd like to see you incorporate the smooth blood effect into the water system, that would be really neat, and I wish the smooth blood wasn't so large, it sticks out and looks kinda unrealistic.
To be honest, this one glitches much more than 2. Although it says more bug fixes. I went from 41 FPS to 3 then my head symbol flew across the screen along with my arms and the arms of my enemies. Also some of the weapons need to be fixed, for example, the Uzi. The next gen mod, though buggy, will always be my favorite mod out there. [Constructive criticism :D]
You can go past the giant easter egg labeled Fig. 0 By going through it where the zig zags and dots are. But do not hit the dots. Once you do that, if you travel more it will kill your bike then say end of level. Just spoiled the easter egg. :P