Quick list off the top of my head from a year+ ago when I last used it properly:
-Native BLUFOR tracking of ALL units carrying a cTAB item or mounted in a vehicle, displayed only on the cTAB devices and not cluttering up the main map.
-Able to place SALUTE markers. Basically, navigate a coupla list options and it automatically places timestamped markers showing hostile position, movement, size, type etc etc.
-Ability to watch feeds from helmet cams that individuals in the field have equipped - can be handy for command, but mainly just a glitzy feature imho.
-View UAV footage from the tablet, lets the commanders just peek at what the UAV sees without having to fuss about taking control of it.
-Slightly more advanced map tools, stuff like ranging and waypoints.
-Higher contrast map, good for many people but worse for some forms of colourblindness (like I have)
-Can "text" individuals using the tablet, keeps sidechat clear if you just want to poke your Charlie to ask if a Whisky is available for reinforcement drop.
I'm personally of two minds about it. It's a nicely put together system, but I don't really see much benefit of it over proper use of the map etc. If people could just learn to place spotting reports properly...