Is it worth coming back to the game?

Yeah right now in patch 1.6 there's an awesome new area to explore and it's actually limited-time (only available this patch) so don't miss out! They just added skins to the game too and you can get a free Barbara skin this patch by collecting conches (will cost money after this patch). Next patch is rumored to be the release of long-awaited Inazuma so the game's in a pretty exciting place right now.

Also if you quit 4 months ago, that was before the new housing system where you can decorate and gain weekly resource rewards plus companionship EXP.