I got him to 5 stars, gear VII, Abilities at 4. He's got good health (12k), his assist is nice and he hits decently (2k non crit 4k crit) plus still room for improvement. If you have some hard hitters on your team, even better. He's great for GW and DS missions for his survivability. Arena he's still too slow. If you have a good team and you're fighting a good team, he'll go 10th on the first round. He won't do anything at all if he get stunned on turn 1.
I'm casually levelling him because I like the idea of an assist heavy team. At level 90 he'll be a beast, still slow, but a beast. If QGJ's leader 8 ability holds up, it may give him a much needed boost.
I would say farm him because he's useful in GW and DS missions, but only if you have a solid arena team first. Plus I'm not super thrilled with any of the available heroes left to farm in GW. I guess you could say I have a bit of a soft spot for Tusken Raider haha.