You can see it during an eclipse. It is red (from H-alpha emission).
It is less dense than photosphere. The lower layers of the chromosphere are cooler than the photosphere, but then the temperature increases with height.
It is also pretty transparent, which is why we see through it to the photosphere.
It has big convection cells ("supergranulation"). At the edges of the supergranules one sees gas spikes called spicules. Here is a cartoon (not to scale)
Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA soper@bovine.uoregon.edu