In a nutshell: Oblivion is a massive RPG that will keep you entertained for a very long time.
Why you should play it: Some of the best graphics the next-gen systems have to offer. Huge interactive world with so much depth and attention to detail. Wonderfully composed musical score. Combat system is great and much improved over Morrowind. AI is top-notch. Tons and tons of side quests. Extremely high replay value. Knights of the Nine adds quality quests and content that you would expect from a great game like Oblivion. Shivering Isles includes one crazy new world to explore along with an excellent new crafting and items system. Draws you in whether you are watching or playing.
Why you may want to avoid it: Loads quite often but understandably so. Knights of the Nine is much shorter than Shivering Isles or Oblivion’s main quest. Shivering Isles can be simplistic and annoying at times.
Final Thoughts: There is really no reason to avoid Oblivion unless you do not want to get sucked in to this addicting RPG. Bethesda has done it again. This should be in every gamer’s collection and is well worth the current $30 price tag.