Its nice! It could use some polishing but its pretty good for a start. I suggest you use the 1 brick high rounds as sand bags. Also, make more of an established perimeter. You have more stuff pointing inward and it should be pointing outward. Don't be afraid to add debris to your building! I can provide examples of how to do that if you want, but just remember a bomb did that damage! Have some fun! Add broken glass, wood debris, rocks, etc. You name it! Or even replace a few of the 1x2 bricks with a 45 degree ramp to simulate "bullet holes."
Hope I can help! Im a World War Two fanatic, lol. This is basically the only thing I build, and I used to have a clan based on WWII. So yeah, let me know!