I think it's a good start for a new mapper. The map doesn't leak, the boxes, barrels and planks are aligned, the entities and the entity settings are great, and there are even models. A few more stuff and ways would be cool, though.
I'm still not sure why you're using so many base entities. Normally one base entity for each team should be enough. More to do:
- you need to mirror the angle values of the red player spawns
- you can rotate models (especially the shrooms) with "angle" "#", too
Map is online @ [OTB] Beta! You can start the map with the command "newmap beta/gp_b1", tell me if you need the login.