BS their art department is very good, and encounter/level design in most games reaches genius levels at times. can't comment on the engines, since this is the first game to use an in-house engine. so what's left... character development is usually good, they have good designers working on their leveling systems. what else... I guess one could say their games lack polish, but that's understandable at least, though not excusable of course.
what do you mean by "mediocre or worse"?
what crusade?
the only people who really enjoyed FO3 were those who had never played the originals.
The art is hit and miss, and not helped by the myriad of horrible engines. The quests/encounters are cool, level design has been from horrid to functional from what I can recall. The mechanics have actually been awesome(discounting the numerous bugs), I especially dug the AP perk system. But yeah, the writing is the main thing that stands out in their stuff, if anything.
As for the FO3 comment, shots fired (and already returned).