Best open-ended RPG ever conceived. All other RPGs pale in comparison. PC Version: more patches & Community support.
Oblivion upon its release was plagued by numerous flaws, like floating objects, quest-related bugs, and glitches that could be game-breakers. But Bethesda Softworks thought ahead, and engineered Oblivion so that the Player Community could write their own modifications for the game. In addition to the Official Patches, the Community developed three Unofficial Patch Mods: one for the game itself, one for the Official DLCs, and one for the Shivering Isles expansion.
These Unofficial Patches are essential to any PC owner that wishes to add Oblivion to their game collection. The Unofficial Oblivion Patch (UOP) alone fixes in excess of 1,800 bugs and glitches (from what was remaining after the issuance of the last Official Patch - 1.2.0416). Potential buyers of Oblivion take note that these Unofficial Patches are revised to work with Official Patch 1.2.0416 only.
Oblivion enjoys a huge fan base: this is clearly evident once you visit the websites that host the thousands of available player-made modifications. These can range from adding a new weapon or item to the game, all the way up to a complete revision of an established Guild, a completely changed city, new NPCs, new dialog, even brand-new Guilds and quests. You can even find a Mod that allows you to summon, mount, and ride a flying dragon throughout the land of Cyrodiil. Want to teach your companion a new spell? A mod was made just for that purpose.
Advantages such as these place the PC Version of Oblivion head-and-shoulders above the 360 and PS3 Versions. And if you find yourself wanting even more, PC Oblivion sports a Console (the "~" Key), that has been programmed with a slate of extremely powerful commands: you can free a stuck player character, resurrect a fallen companion, add any item to your Inventory - even clone your character. You can move to any location in the game, move any NPC to your character's side, or vice versa. Want to change the weather? You can do that with the Console as well.
Oblivion is also one of the most hotly-debated games ever to be marketed: and the game is as popular today as it was when it was released in 2006 - not many games can still make that same claim. There are 3rd-party utilities for Oblivion that are still being revised to this day, and retailers still carry the game on their shelves. I believe it's very evident that Oblivion will remain one of the most popular (if not the most popular) RPG ever made.
If you noticed that I did not get into the actual gameplay, it is because that is covered very well within the Gamespot Editor's Review. I chose instead to cover what has been done with the game since it's release, and the support from the Player Community.
You can't go wrong if you get Oblivion for the PC. With thousands of glitches patched, and thousands of available Modifications, the end result is a RPG with nearly everything you could want or imagine, along with every possible gripe modded to your satisfaction.