There is simply no other game available for the PS3 which equals the enormous breadth of content, scope and freedom offered by The Elder Scrolls IV: Oblivion - Game of the Year edition. It will take you literally hundreds of hours to complete every quest and to discover and explore every location. Character creation is excellent. There are ten different races and even more classes to choose from. You can create your own class if you so wish. The game world is enormous and beautifully realised. There are flower-filled meadows, snow-capped mountains, eerie caves, bustling towns and villages, crumbling ruins, ancient haunted underground cities, infested swamps and of course the hellish demonic world of Oblivion waiting to be explored.
Freedom is the name of the game in Oblivion. The moment you emerge from the dungeons into the beautiful world of Cyrodiil you're free to do as you please. You can completely ignore the main quest if you want and simply explore the world, picking up the odd side quest whenever you feel like it. The quests themselves are fun and varied. There are also guilds to join, homes to buy and furnish, items to discover and trade, monsters to be slain.
It might sound corny but there are some genuinely special moments to be had in this game. The combination of the award-winning ethereal soundtrack, and the gentle breeze moving through the long grass as you watch the sunset makes for gaming heaven. Of course, a game as large as this will inevitably have some flaws. A fairly small number of voice actors were used, which can spoil the immersion a little bit. You'll also encounter the odd random glitch, but nothing game-breaking. The vampire glitch as mentioned in other reviews ONLY occurs if you are a vampire AND you are completing the long optional quest to cure your vampirism. All that happens is you remain a vampire. You can continue to play the game as normal.
You will not get a better value game for the PS3. It will keep you occupied for a very long time, as there are so many ways to play it and you will constantly be discovering things you missed out on previously. Go on, enter the world of Cyrodiil and begin your adventure. You won't want to come back.
Edit, March 2013: Graphically the game has aged a bit, in particular the character models and some aspects of the landscape, eg. snow-capped mountains, all of which have been improved substantially in Skyrim. However, this remains one of the best games I have ever played.