It doesn't match Oblivion's epic adventure but it's still a whole heap of fun.
The game does create the illusion of being huge but it really isn't. The main story is very short and the ending caught me completely by suprise. There are quests and they are a lot fun to complete but I was annoyed that one quest in particular (the survival guide researcher) did interfere with the main story and I skipped ahead one chapter because I talked to a character I wasn't supposed to talk to until later in the story.
The graphics are great but wondering around a post apocolyptic landscape for hours at a time does get very depressing. The sound is also excellent, especially the radio stations which add most of the atmosphere to the game. It's still a mystery though why 2277 looks and sounds like the mid 1950's. A better option would've been to set the game IN the 1950's on a alternate timeline.
Overall it's a great single player experience that you will play for hours at a time. But it doesn't last long enough. Oblivion is still the best RPG for the Xbox 360.