Biomes: They have brought 7 different biomes to the update. These are Jungle, Roofed forest, Mesa, Savannas, Taiga, Mushroom Island and River. 

Generated Structure: There are a few new structures. These are Caves, Lava pools, Villages, Stronghold and Abandoned Mine shafts.

For the rest, go to this site: minecraftpocketedition.wikia.com/wiki/Update_0.9.0

My thoughts on this update is that they added a huge range of new features. They have added flat and infinite terrain. Now this is something that alot of pocket edition fans have been waiting for. But the one thing we need, is an easy login. Login is way too hard since it only assumes you have registered when you have been on your first server, and if you quit that server, you can't ever login.

This has effected many of the players who buy the game. But other than that, the new advanced option can let us choose any terrain out of Old, Infinite and Flat. They have added new blocks such as granite. Another thing they need to fix is the mining bug. When you hold your finger at the bottom of the screen, it will mine at the top making this a huge issue for mining. It is more likely they wont fix this bug until version 1.0.0 or slightly earlier.