They're saying it looks like a graveyard because those obstacles look like...uh...headstones. You could use round 2X2s for sandbag piles or 3 height bricks for small walls instead.
It looks bland because there is no detail to the build. It is basecubes, obstacles, colored team spawns, and a center platform. The entire build could use some decoration. We can't really explain to you how to do this, it just requires some creative thought on your part.
One method I like to use is to give a build a Tron-ish / laser feel by adding the glow effect sparingly to minor outline features (like plate bricks outlining stairs, a doorway, or a perimeter of a significant area).
