Looks pretty good for your first map.
Nice to see that you tried to align all textures and added clip brushes now. Only the same rock texture everywhere might be a bit boring.
You can delete all barrel items, because players already spawn with steel barrels
Some screenshots:
Red: Move the texture down a little bit, that the planks aren't splitted.
Red: Looks like there's a wrong texture. I think that should be the rock texture there.
Red: I'd add two more clip brushes here.
Green: Move this texture a little bit to the left, that the texture (with this points) isn't splitted.
Red: Move the texture down to the ground, that it fits with the original one. You can have a look at the small black line between the first and the second ring. This should be on the ground.
Green: Hm...I don't know if you know that a brush can have different textures, so there's no need for an additional brush with the top/bottom texture. Choose you texture, press CTRL+SHIFT and right click in the 3D view the face you want to have with this texture. That's all. You could do the same with some gras textures.
Red: There's a small space between the light and the ceiling. It's almost the same on the other side.
Red/Green: This looks very improperly. Move the texture faces, that the dark faces fit with the dark faces and the bright faces fit with the bright faces.
Map is online @ [OTB] Beta Server!