very nice,
but few improvements can be made for next diorama:
first, the road is too straight. you should put it a bit more diagonal to break the symmetry. also, break the tree line.
second, there are too many open spaces. a diorama is better off without them most of the times - unless there is a specific role for them.
I would have chosen a narrower base, and put the road diagonal to it.
the alst thing I would add are soldiers - to give sense of scale and liven it up a bit.
as it is, it is a very ncie diorama, and to make it even nicer I would have added some figures marching or sitting and looking at the tank while resting.
no offese, just positive criticism.