Fallout New Vegas was everything I had hoped in a Fallout game - it had roleplaying choices out the kazoo in every quest; multiple ways to solve (some quests had 8+ ways of solving/branching endings); factions that mattered; tons and tons of deep sidequests/main quests that intertwined and the dialogue was excellent.
FO3 had a nice atmosphere for exploration and survival play but that is about all....... in my opinion only. It had flat NPCs, minimal dialogue, no real factions w/quests, few side quests, low lore re: Fallout universe etc.
I hope Obsidian is given the chance to make a companion game like FO3/FONV ........