If you've actually looked at vanilla Oblivion by itself it's really just a mediocre rpg. The reason it has so many fans and has lasted for a long time is because of an enormous modding community. With the help of mods, Oblivion has been pretty fun for me. If you like Fallout 1, Fallout 2, all the weird spin-offs, Fallout 3, Fallout plush toys and gummybears, you'll probably enjoy FONV.