It's not bad for a first blaster it's pretty good. But as the person above said the edges are too sharp. a wireframe and a darker background render would be nice.
Gotta love the companion cube! Any chance of smoothing out those edges slightly, there are definite edges on the actual cube, not sure if they are that sharp.
Looks good now, but the cracks make no sense. They wouldn't appear in the middle without connecting to the sides, and there should be more sharp turns, not curves.