Visually - everything either looks like crap or the inside of a horrible airport hotel (ie, The Institute). FO3 at least had some style (the art deco/Metropolis-ish stuff etc etc).

Exploring & quests - apart from looking like crap, most of the interiors are uninteresting shooter levels & the quests are almost all: go to crappy uninteresting place/kill stuff/loot/return. It's just tedious and rather unpleasant.

The overall story is just horrible. Generally you are forced to betray and kill more-or-less innocent people if you want to progress. I don't see a way of playing through the game without either feeling lousy in the end or else feeling like you've been pushed along a railroad by an inept storyteller who thinks this kind of thing is "edgy" or whatever.

A massive, inexplicable production fail, IMO.

The other game I've played recently is Dragon Age: Inquisition. The two are kind of comparable, I think. Both are overstuffed (crafting+RPG+action+whatever, too much filler content); both are massively flawed in many ways; both seem to get a similar reaction (eg their Metacrtic scores). But I ended up liking DAI a whole lot, despite everything. It looked good, locations were varied and often interesting, the writing was less crap-television-standard, and some of the character writing was actually quite excellent; it had charm. On the other hand, FO4 for me is just ... unpleasant.