Here's a few issues I saw:
No draw textures.
I feel like this should be a ramp or stairs. It gets you to basically the same place as the other side (which is some stairs and then the barrels to jump on.) If you know what I mean.

I don't see anyone taking this side if it is more efficient to take the otherside instead.
These just look odd to me for some reason. I think they need bottom support or something of the sort.
This spot was obnoxious to me. There needs to be more room to get around the stairs, I think.
Just some ideas.