Biergarten is my family's one absolute "must do" at WDW. We love the food & the friendly service, and the entertainment is our favorite of any WDW restaurant. From DS2 & DD5 to both my wife and I, we universally look forward to dinner at Biergarten.
Cape May is fine, in my opinion, but the seafood is nothing special and the atmosphere reminds me of a Marriott restaurant. It's not bad, by any stretch, but it is by no means distinctive or special.