fallout 3 doesn't suck. it just hasn't aged well and new vegas is a vast improvement on the combat mechanics, which is like the only mechanic gamers really care about
it definitely had a more coherent plot of start here, go there, finish here, rather than new vegas' deliver this stuff, go talk to that faction, assassinate this president. it felt like an actual story while new vegas felt like a really long and underwhelming delivery that ended in a really underwhelming boss fight
it was much better than the fight against autumn