This is a fun add-on to Skylanders Giants, and includes a cool magic item and two enjoyable but not dominant characters, which I'll describe separately. First, though, a slight word of warning. While these three toys are compatible with the Skylanders Giants game, it does not include any actual "Giant" figures, just the three figures listed below. Also, unlike the Adventure Packs in the last game, this battle pack does not unlock a new playable level, just a new battle mode area for PVP fights.
1) Silver Cannon: This is a "magic item" that you can use in the game for approximately for approximately 45 seconds each time you play a level. (You will see a circle on screen winding down the time, and can remove and re-add the cannon until your time is up.) If you add it to the portal, a cannon will appear in game, follow your Skylanders around, and shoot blasts of flame at your enemies. It's helpful in the boss battles and is also just fun. Adding the cannon also unlocks a new PVP battle area. Note - another store has the exclusive right to sell the limited edition version of this pack, which comes with a gold cannon instead of silver. I'm not sure what the difference is, if any.
2) Shroomboom: This is a new life skylander. He's not the most powerful, but he's very cute, so we've been playing him a lot. He shoots explosive mushrooms with his slingshot, and can raise a defensive ring of mushrooms to slow down enemies. As you power him up, he gets more mushroom abilities, like a different explosive mushroom and the ability to launch himself at enemies. As I said, he doesn't dominate, but he's cute. After upgrading, Shroomboom can hold down his z-button to continually spam the screen with "paratrooper" explosive mushrooms, which is different and actually sort of effective, assuming you can still see him well enough to avoid the enemies while you wait for them to blow up.
Note: Shroomboom is not currently for sale as an individual figure, but he is on the list to be released in a "lightcore" version later, so if you're planning to collect the lightcore figures, you might want to wait.
3) Series 2 Chop Chop: This is the updated version of one of the undead figures from the original game. As in the original game, he's a sword and shield wielding beast. He does reasonable damage and his shield can protects him from most threats. He's basically the same as Series 1, except that he has access to a "Wow Pow" - in his case, an upgraded shield bash.
Lastly, although you can use Chop Chop in both Giants and Spiro's Adventure, the other two figures are only compatible with Giants. Enjoy!