there are a couple of edges in the main struct that look a bit odd, except this it look nice althought I'd make some little more detailed guns: the barrell for example could benefit of a larger tip, and the turrett base could be less blocky or have more detailes
anyway..topace, you are right, there are more important models that should be redone, but I think that kracker's intention was to gain experience, and the best way to gain experience is to make practice, starting from the very simple models
And don't forget that with lods you will hardly see lod0, there will be almost no performance hit at all from this thing.