Not bad for your first crack at it, but there's a lot of weird things going on there, but as you get more practice, you'll improve at it.
One thing i'd suggest watching is
this VTM. Sure, it's quite a big download and runs for a few hours, but i found a lot of it exceptionally useful in learning to model low poly weapons in 3ds, and as a product of that i made
this model, which isn't bad for my first go.