The DVD contains 8 add-ons to Oblivion, each of which can be loaded separately. They can be broken down in to 3 groups, Quests, Real Estate and Equipment, so I'll tackle each group in turn. Warning, before you read on, my review does contain specefic information about the game, which some may consider minor spoilers.
Quests x3: The Knights of the Nine (completion: 8ish hours) sends you to multiple dungeons collecting things, before battling an ancient evil foe and saving the world, the usual kind of grand plot. There are some nicely designed dungeons and at the end your reward is an armour set, which is either light or heavy dependant on your own highest skill. It's not particularly good though, although it does have one nice effect, which is to stop wild animals attacking you. Minor gripe: some of the voice acting is too quiet, leading to constant fiddling with the volume. Mehrune's Razor (completion: 4ish hours) Just one dungeon, but it's absolutely huge, contains a whole village in one cavern; the reward at the end is a very powerful dagger. Minor gripe: the lighting seems brighter than dungeons from the original game, not to my liking, but no big deal. The Orrery (completion 1ish hours) amounts to a handful of skirmishes with bandits to obtain parts to fix the Orrery at the Arcane University. Once fixed the Orrery grants you a spell to give one of your attributes a large boost, which attribute is dependent on the moons phase, the downside is it also cripples another attribute by an equal amount.
Real Estate x3: All 3 properties fall in to your ownership for free, via various stories, however, buying the upgrades require substantial funds. The Wizards Tower highlights: huge storage area, altars for enchanting, spell making & Atronach summoning, garden of alchemy ingredients, harvest Imps for Grand Souls & teleport to any Mages Guild Hall. The Vile Lair highlights: prisoner for Vampires to feed from, bathing pool that cures vampirism, shrine that cures disease etc... like a church altar but only evil characters can use it, your very own minion who will go out an kill on your orders and bring you back the loot. The Thieves Den highlights: set on a pirate ship with full crew, all crew members have useful training skills or good items to sell; think you need to reach a certain mercantile level for some. Practice chest for and increasing lock picking skills. The crew can be sent out pillaging and will return with your cut.
Equipment x2: Horse Armour, a vendor sets up business selling the said item, you get a freebie for starters, but can buy more if you lose your horse, comes in 2 designs and offers decent protection to your horse. Spell Tomes, these books start turning up in random loot, when you open the book you read the spell and decide if you want to learn it and add it to your permanent list. Spells range from weak to powerful, so you won't want to add them all, so far I've found a couple of goodies.
Summary: Some entertain new quests adding a good few hours of game play, a nice selection of real estate to add to your portfolio and a couple of useful new equipment types. The only thing that seems to be missing is a property for the fighter type character. Still, for the price you can't really go wrong, even if you only decide to load half of the add-ons. Not quite worthy of 5 stars, but still very good!