ES4: Oblivion - Review @ YouGamers

Presumably YouGamers is a play on YouTube...either way they have a review of Oblivion with a score of 91%, declaring it the "current pinnacle of first person, role playing games":

The past iterations have all been known to allow the player to assume any role possible within the game's limits (such as a knight or an evil mage), whilst taking on quests from a series of guilds, or other entities. The main quest was always optional and the gameplay never depended on it as much as in other RPGs. All episodes of the series are based on the fictional world of Tamriel and each one expands the already complex Elder Scrolls lore. The previous episode, Morrowind, received two expansions and was universally regarded as one of the best open-ended role-playing games of the past years (although it did have its fair deal of issues and shortcomings, these were easily compensated by its virtues). The latest instalment in the series, The Elder Scrolls IV: Oblivion, is no exception to the general concept of the series.