Indexed Universal Life -- Benefit from Bull markets and avoid Bear markets? Too good to be true?

I've been hearing about this technique on the radio a lot and I wanted to hear the opinion of r/investing. They claim that during bear markets you won't lose anything, and actually still gain 1-2%. But during bull markets you will be paid out equal to the index of the S&P 500 or whatever index you choose, up to a maximum of 12%-15%. This sounds too good to be true. What am I missing?

http://www.investopedia.com/articles/insurance/09/indexed-universal-life-insurance.asp#axzz1ybVYiS3W