Dominion: Prosperity is the most recent expansion to the Dominion series. You will need Dominion or the Dominion Intrigue base set to play Prosperity.
Dominion: Prosperity is an absolutely stunning addition to the Dominion card game series. Prosperity not only adds incredibly interesting new cards and strategies, but this expansion revitalizes the original Dominion set, the game we all know and love. A decent number of the original Dominion kingdom cards have added purpose and strategic value and many are, at the least, nice, low cost cards that compliment Prosperity's high priced actions and treasures. If you do not yet know and love Dominion, I see three strong possibilities: 1) You are reading the wrong review, 2) You have yet to purchase the original Dominion game (link above), or 3) You have played Dominion to death and are bored with it, thus confirming the "know" arena much too well and replacing the "love" relationship with "love-hate". Regardless of where you fall, here are some of the basics (spoilers ahead).
The most noticeable additions to the game are the new larger treasure and victory card, the Platinum and Colony cards, respectively. Instead of making the Platinum worth 4 treasure, we find it worth 5 with a cost of 9, and the Colony worth 10 victory points, costing 11. To win the game, there are now three standard conditions available: the Colonies pile is diminished, the Provinces are diminished, or 3 (/4) kingdom card piles disappear (2-4 players, /5-6). Beyond that, it adds 25 new kingdom cards that are beautifully illustrated, well balanced, and, for the majority, not overly complicated, which is an amazing feat in and of itself. Several of these are new treasure cards that are not placed among the base Treasure (like the new Platinum or the Potion in Alchemy) but are included in the 10 kingdom cards chosen for play. These creative treasure cards include an "action" of sorts (but do not cost an action to use), adding the strategic element of playing treasure cards in a particular order to reap the maximum benefit. Another major addition is that of the victory point "mats" along with a few different opportunities to gain victory point tokens throughout the game, represented by numbered metal shields. These tokens remain on the mats until the game conclusion when they are counted along with all of the victory points in hand. Lastly, now there are action cards costing more than 6 available for purchase on the table. Bigger cards, bigger money, bigger victory points. What could be more fun?
Other subjective bonus horrahs: only one card dealing directly with curses, a couple of great attack cards, excellent kingdom card artwork, nice metal tokens, thorough turn example in the rulebook. Quibbles: Victory token mat artwork recycled and oddly cropped, base Treasure cards (including the new Platinum) are all the same "gold" color in U.S. versions, victory token mats do not fit well in the box. Neutral thoughts: Potentially longer gameplay time. All in all, it is hard to objectively find anything bad to say about it. Note: MSRP is $45.
If you simply cannot wait to find out what the cards are, you can find the complete description list on boardgamegeek. To do the cards justice, though, you really must see and touch them. I highly recommend it.