Season pass is a better choice.
Hidden Secrets is the first downloadable content for Assassin’s Creed 3 and it adds a lot of new content and provides a different perspective to the main campaign.
If you own a season pass you can download this first piece of content on December 11, based on when the respective store for PS3 and Xbox 360 refreshes.
The DLC adds three extra missions providing an hour of gameplay. The missions are: Lost Mayan Ruins, the Ghost of War and a Dangerous Secret. There are goodies too for completing these missions. You will receive in-game weapons and two single-player costumes including the fabled Captain of the Aquila uniform and the traditional Colonial Assassin outfit, and also two multiplayer characters including the fearsome Redcoat and the deadly Sharpshooter.
It is better if you buy the season pass and if you are interested in playing all the future content that Ubisoft will release. The season pass will cost 2400 MSP or $30 on PS3. It will also be available on the Wii U but at a later date.
The next DLC pack is slatesd to arrive soon and will feature George Washington. You as Connor, the assassin, must take him down and end his tyranny. Personally I am really excited to play this pack.
You can check out our review of the game over here.