Working fine on iPhone 5 with beta 3. Listened to a few 2+ hour podcasts while doing other stuff on the phone without any issues. Like someone else mentioned though, the search function is non existent in the "store" when trying to find podcasts I'm not already subscribed to.
If you're having issues, try deleting the podcast app and installing it again. If that still doesn't resolve it, try going to Settings - General - Reset - Reset All Settings.