This might work for a quick 1-on-1, but the fact is that it is simply far too linear for a multiplayer map. It's really just a series of empty hallways that lead to dead ends. This might work for a quick (very quick in this case) singleplayer romp, but not for multiplayer. Take a look at the official maps, or some of the ones uploaded here. Multiplayer maps should contain loops and branching paths. Players need to be unpredictable in deathmatch in order to have the edge, and as such the map needs to give them options. Alternate paths to the same locations, choke points and larger open arenas.
I understand that this is only a practice map, but you should also learn from the criticism that goes with it.
I understand that this is only a practice map, but you should also learn from the criticism that goes with it.