I played a test game with Chewie in the simulator and think he is not only much better than I initially thought, but a real game changer for rebels.
Teamwork Han is not bad of course, but his real selling point is Guardian 3 in the context of a rebel army and together with Reckless diversion.
A lot of key units have a relativly high damage output, often a relativly short range, are relativly squishy and loose output fast if they loose miniatures.
This is the case for Han, Luke, Wookies and Fleet Troopers. Unfortunatly it does not help as much with Flamer-ATRTs.
You put Chewie behind a los-blocker, but in range one and in sight of one mini of your assets that are supposed to remain intact and deal damage.
That way you do not loose damage output by taking damage until Hans reckless diversion kicks in in the turn that you commit and close in.
It is also great to protect sniper teams in the turn your opponent plays Maximum Firepower or Coordinated Bombardment.
He may have the potential to become as pivotal as Biggs was for a lot of Rebel lists in X-wing 1.0 for a while.