The feat is hardly ruined. Many would claim it is still too powerful:
Divine Favor
Divine Power
Righteous Might
and a few I'm sure I forgot
You don't need persistant Bull's Strength. In fact, its an incredible waste. By the time you're casting 6th level spells, you can extend Bull's Strength (et. al.) for only one level increase and get them up to 22 hours or more.