I always used Kayak for air tickets search. I might continue using them, but for search only, I will never book tickets through Kayak since 24 hours free return policy doesn's work with them! They will charge you $50 for each booked ticket! It never happened to me before. I always use 24hour return policy, It gives me time to make my final decision. Also you can check reviews of the company Kayak is using to sell their tickets: chatdeal, I think its rating is 1,5 star... it says a lot!