I didn't find skyrim to be as good as oblivion, as far as immersion and general re-playability is concerned. Even the guild side-quests in oblivion were longer and of higher quality than the whole skyrim main quest-line. Everyone of the guild quests in oblivion were a real treat, can't say the same about pretty much any of the skyrim quests, they were just not as fun.
Oblivion kept me playing for years, the main quest-line and guild quests were that long. Skyrim is now just about the mods. Even the music from skyrim is no where near the same quality as that from oblivion, even though Jeremy Soule did both, I wonder what happened there. The only thing Skyrim has on oblivion is visuals.
If you don't already own oblivion then I would definitely recommend it.