Those bridges are much too arched, and it's quite bland. Find some inspiration, if you want some help you can contact me via skype. My skype is in my profile
The walls could use more depth and detailing, with the walls on the second floor (or roof level) they are very flat and plain, try adding some designs and more shape to it. Overall, it's pretty good though!
Hey, I'm a member of a BT called Novus, before I forward this to the manager of the team, is this a paid commission? We've worked with "fabtob1" who has a youtube channel. He's made multiple maps that have been featured on "Ethoslab" "Vikkstar" and others such as "Docm77". Get back to us as soon as possible and we may be able to organize this build for you with an appropriate price based on the scale, thanks.