Certainly not as bad as Horse Armor, but...
The Orrey is one of the two initial DLC packs announced for Oblivion, with the promise of being able to see inside the locked door at the arcane university and go on some sort of adventure. It certainly sounded better than horse armor, which to this day is one of the better examples of overpriced and unneeded downloadable content. After all, The Orrey must be way better than Horse Armor, right?
In actuality, The Orrey is a bland 15-minute quest that consists entirely of going to random bandit camps, killing everyone there, and repeating until the quest is done, at which point the "reward" is a once-a-day power that increases one stat by 20 but also decreases another by the same amount based on the phases of the moon. While not totally worthless, the reward is too circumstantial and bland to make The Orrey be worth downloading. Ignore it almost on the same level as horse armor.