Once you update the Playbook to 2.0, you can run basically all the Android apps that were developed on Native Development Kit for Android. Plus it gets native email, native calender support, and contact saving without BB Bridge.
Android 2D games will also run on it.
But some Android softwares will be unstable, and rightly so, because some apps might have some part of coding not developed by Native Development Kit.
For more info, check out Crackberry (check their blogs at 2nd or 3rd page, about Updating PB to 2.0).