I'm going to guess that this isn't for a game, based on the high resolution of all the circular objects and the reflectivity on the front surfaces. I will offer critique with that assumption.
PRAISE: The overall geometry is excellent, with good color choices and a nice framing of the object for the picture. You've got decent lighting that really emphasizes the details of the model, and the angle of the vehicle is also appropriate.
CRITIQUE: (In order of simplest to most complex.) The object isn't centered in the image, which is distracting because we expect to be looking for something in the over-emphasized left side of the background. The materials need more work; the reflective surfaces (like the hood) are too mirror-like, the non-reflective surfaces (like the tires) have too much specularity, the gun barrel simply isn't dull enough, and every single color could do with just a little bit of "noise" with a similar color so it resembles a realistic colored surface (like paint). Right now, the color looks like an intrinsic material property (like green quartz or bare gray steel). Finally, and this is the challenging part, BEVEL your edges. Nothing says, "I'm a 3D render" like those infinitely-sharp edges on the gun-scope, on the tire edges, and on the gray support structure over the cockpit.
Overall, it's an excellent model for a beginner-to-intermediate level, and certain advanced-level refinements could *really* make it shine.