I don't think it looks like the Halo tank at all. In fact, if you look a bit closer than "barrel + threads = tank" then it's not remotely the same.
This one has a much more high-tech feel to it. Almost all the surfaces are rounded, there are a couple of sperical shapes in there (for instance the 'hinge' on the side, in the middle).
Also, the turret has a very clear vertical-oriented shape to it, while the Halo tank is very horizontal-based (just look at the air intakes or w/e they're supposed to be).
This one looks like it can actually be used as artillery due to the range of freedom on the barrel.
That said, I'm not too much of a fan of the main body front. It looks too much like a goofy SUV/soccer mom car hood and too little like it's serious business
If you were to lower that a bit, or at least make the profile a bit more slanted (make it ' bite', lean forward a bit), as well as change the chrysler-style grill to not look like a regular car's it would look really badass. Now it's a bit like a regular car with tank threads and a turret plopped on.