Very nice, clean and simple. And I like clean and simple maps (Garden ftw). It could use more details, but maybe you were going for the simplistic look of Counter Strike or even Assault Cube (I've barely played and CS so I could be totally wrong about that). Either way, it looks like a throwback to some 90's game, which I actually really like. The geometry could use some work, especially the terrain. Also some parts where they are clipped off could use some barrels or some sort of physical barrier so it makes more sense, rather than thinking you can go through but you can't. I also like the uniqueness of the map, so +points for that.
I vote 7/10
Edit: Since I missed some of the voting rules, I change my vote to a 5/10. I really like the map, but I don't think the quality can compete with some of the maps in this challenge. With that being said though, I hope you keep it up.