Works great for multiclassed worlocks. I have Wyll as a level 4 warlock and currently a level 1 bard. He uses his warlock spell slots first and then he can cast his bard AND warlock spells using his bard casting slots. Gives a warlock many more spell casting. Short rest he gets his warlock points back. Singing warlocks are much more powerful and the loss of a feat is made up for with triple the spell casting. Also the warlock spells when cast using bard slots will cast at the warlocks level.
