Not bad, being your first map, but of course you have something to learn to improve your work.
Strange gameplay, having only slams and stunstick, it would be better to add a gravity gun, to use all the physics you've put in the map, enhancing fun and gameplay.
The map is leaked, because some brushes are not sealed. There is a gap in the floor, and even some walls are not united, you can see the void (endless mirror effect) between them. That brings to a bugged map, because vvis cannot be performed in a leaked map, causing no optimization and lower framerate. Even the black faces here and there are probably due to the leak. You must to get used to build on grid, to avoid any gap between brushes.
Take more care in texture alignment, too. Expecially using tile textures, like your floor, misalignments are particularly visible.
To optimize the map turn to func detail every irregular, not covering brushes. Stair steps, columns, small blocks must be func detail. Does not change much in such a small map, but it's good to acquire method and correct habits.
Learn to read the compile log, and never release a leaked map, find the leakes by "load pointfile" Hammer's function and correct them.
I hope this will be helpful in improving your future works, cheers.