FO3's writing was awful. It was good to see Bethesda at least trying to offer skill checks during dialogue but they failed to do them well. They also failed to write believable locales or interesting companions. It's like the writers thought "Hey, wouldn't it be cool if..." but then failed to make the answer a coherent and logical part of the lore and setting.
As mentioned earlier, the only thing FO3 did better than FNV was dungeons and that's only because there was a distinct shortage of dungeons in FNV. The few ones that they had were great. I'm disappointed that Bethesda will be making the next Fallout instead of Obsidian, since I doubt their writing has improved.