Oblivion is a beautiful game, but an overall shallow experience proves great graphics do not make a great game.
There are also a number of other skills that you can utilize in the game that enchance the experience. You can craft potions, for instance, to grant you temporary bonuses to your attributes or new abilities.
Finally, there is a huge amount of content to explore in Oblivion, and it takes a free-roam approach to it all. This sandbox approach to the game is a great benefit. While it doesn't make the game any less linear, at least you don't always have to take the same path from quest objective A to quest objective B.
Graphics: The graphics of Oblivion are indeed beautiful. Forests look serene, dungeons look dark, dank, and gloomy, and the weapons and armor are simply gorgeous. If you have a system up to the task of running the game, Oblivion will most certainly reward you with a fantastic visual show.
Sound: Most of Oblivion's music consists of a mellow soundtrack that doesn't particularly stand out, but the sound of weapons hitting armor, flesh, and shields helps to bring you into the combat. The sound effects in general are well done, but the voice acting is a story on its own.
Every single line of dialog in Oblivion is voice-acted, and while that may sound like a great idea, there are a couple of drawbacks. For instance, the NPCs really don't have all that much to say, and you will frequently hear them repeat their lines over and over (I saw a mudcrab the other day...). Additionally, the quality of the voice acting runs the gamut from good to stale to exagerrated, depending on who you talk to.
Value: Oblivion is jam-packed with dungeons to dive into and lands to explore, but after a while, they all start to feel the same. You'll never really run across a dungeon you can't beat (see the level-scaling issues below), so you'll never be sent packing from a dungeon that is way too much for you, only to experience the satisfaction of kicking monster tail and emerging triumphant once you've gained some new abilities and better armor. Thankfully, the game comes with a construction set, so if you tire of the vanilla version of Oblivion, there will be a mod or two out there that will extend your play time.
Tilt: While getting lost in a first-person shooter may mean boring, irksome backtracking, getting lost in Oblivion may lead to new adventure opportunities, and being rewarded in such a way for going off the beaten path can be great. However, it is typically difficult to be surprised in such a manner as all dungeons, quest objectives, and unique areas are highlighted on your quest-compass, which feels like a blatant hand-holding tool. Not only that, but you can skip the getting lost process altogether by simply fast-travelling to a location somebody marks on your map. While the fast-travel system definitely saves more than a few headaches, it would have made more sense to only be able to fast-travel to places you have visited.
That said, the biggest disappointment has to be the level-scaling system that Oblivion uses, which is quite awful. At times, the scaling destroys any sense of immersion you might get. For instance, at the beginning of the game, bandits will accost you wearing simple leather armor and using mediocre or poor weapons, which makes sense given that their primary income source is demanding gold for a person's immediate physical health. However, once you gain enough levels, bandits will be running around in obscenely expensive armor like glass or daedric and wielding magical weaponry. If the bandits have access to such powerful, valuable armor, do they really need to hit me up for a paltry sum of gold?
The scaling system leads to other issues, which, while not usually outright problems, definitely feel out of place. For instance, it is possible to beat the game as a level 2 character. You can save all of Tamriel, become the champion of the arena, and be the head of all guilds at the game... at level two. If anything, levelling up only makes the game more challenging. If you walk into Kvatch at level 1, the guards and you will easily break the seige without breaking a sweat. However, walk in at level 13, and your guard allies will get stomped in ten seconds flat leaving you outnumbered and flanked by a bunch of nasty demons.
Overall, Oblivion is a beautiful game with a large amount of content to explore and enjoy, but the game itself doesn't feel particularly deep or compelling.