I would strongly urge you to buy a copy. Crank up the difficulty, so you get a good flavourfull chunmk to chew on, and have fun. Certainly there's elements of Oblivion, but ... the best way I can put it is:
I despised Oblivion, and was only able to finish by installing a third party mod, and invoking every shred of my natural bloody-mindedness. If FO3 is Oblivion, then I've changed into a completely different man, because I frakking love FO3.