Trade in old iPhone for new iPhone 6?

Verizon is offering a new deal where you can trade in your old iPhone to get the new iPhone 6. I wanna know what's the catch, has anyone done this yet? What was your experience.

You still have to sign a 2 year contract. It is only available for those who are currently a Verizon customer and their contract is over and they wish to upgrade a new phone (to renew their contract). It is also for new customers who don't have Verizon Wireless. You have to give them your current iphone 4, 4s, 5, 5c, and 5s in exchange you get the iphone 6 at a value of 199.99 which would be free. Your current old iphone must be in working condition. You get the iphone 6 which has a 4.7 inch screen.

Remember you are locked in for 2 years and Verizon has the most expensive plans, with voice and data for a smartphone.