A small, fast map with nowhere to hide, but it plays large because of the number of low walls and other line-of-sight obstructions. Check out the screenshots- most of the map is visible among the 4 of them.
There are several secrets in the map that give you a better vantage point down into the trenches: destructable walls that lead up to a path overlooking the level and invisible platforms above the wall behind each spawn.
Bots are uncannily good at this map- just run nav_analyze (or use the included nav file) and they'll play fine without getting stuck on anything, though they don't use the central tunnel or the secret areas. Download it and give it a try.
Hint: If you fall off the level, don't just suicide- there's a way back in. Also, you don't need to crouch to move through the tunnels, just walk into it.