This looks great but here's my suggestions:

1> the map looks too blurred on the large flat aresas, it looks too much like "Filter>Render>Difference Clouds" Maybe some more noise or something added in would help.

2> The panels along the side look too much like a bump map. Maybe a displacement map or even geometry would help and look better

3> Nice big gun! But it needs a bunch of ammo to be fired from it! E.g. a belt of ammunition would look excellent!

This would be a cool challenge, to be given a model and then everyone has to texture it and see who gets the best results.
I love the tank model though, loads of great details

Alan