Here is the official description of the game:
The survival of the Angry Birds is at stake. Dish out revenge on the green pigs who stole the Birds’ eggs. Use the unique destructive powers of the Angry Birds to lay waste to the pigs’ fortified constructions. Angry Birds features hours challenging, physics-based demolition gameplay, and lots of replay value. Each of the 165 levels requires logic, skill, and brute force to crush the enemy. Protect wildlife and play Angry Birds!
Angry Birds For Windows Phone 7 is Xbox Live enable with Achievements and leader boards. It includes 165 levels compared to the 255 available for competing platforms. However, according to mobiletechworld, the game is identical to the what was already out on other platforms, so be prepared to play exactly the same levels (165 of them ) if you have already experienced it on an other mobile device.
You can download Angry Birds for Windows Phone 7 via