I may be repeating things I've said elsewhere on this site; I don't really remember. In any case, Fallout 4: Far Harbor was decent. Some surprisingly strong writing in parts, a fun location, good faction interplay, and generally speaking the best I could've expected Bethesda to do when it came to aping Fallout New Vegas. The loss of a more expressive stat system really hurt the ability to roleplay, but Far Harbor did a surprisingly good job with what it was given.
The base game, however, is abysmal. It's tedious, full of filler content, with awful pacing and writing. What comes to mind is the modules to Neverwinter Nights that managed to tremendously improve on the base game. I could definitely see modders doing some really cool stories within Fallout 4's engine, which does admittedly have some pretty basically entertaining shooting, but I don't see a ton of reasons for them to specifically pick Fallout 4 to convey those stories. Additionally, I doubt they could ever do much with the limited dialogue and roleplay systems, and I haven't heard of anything particularly interesting releasing for it.