In a few words.. The map is very very simplistic in style and could use more eye candy.
I suppose you just started mapping, but to get good ideas about interesting layouts take a look at runningmanctf or mikectf2. Those feature several ways to/from the flags and offer a dedicated base that holds the items and houses items to help with defending the flag. There is also usually a spot in the center with an important powerup like shield or quad to fight for.
As for eyecandy, i guess this comes with more experiance in mapping, add a few things here and there. do not use the same texture on huge walls, break them down and change things, add more light, shadow, lightsources with different colors..
Its however quite ok for a start
