I have, and with regards to specifically the Ipad 2 defender, I can not recommend it. The engineering that went into this is sub-par to other otterbox products that I own currently. (Iphone defender, and Ipod touch defender)
Specific dislikes include: the tabs that cover the headphone jack, does not secure properly, puckering outwards and is easily uncovered, the entire rubber outer jacket does not have a secure fit into the channel of the hard plastic case, resulting in the rubber unseating itself with nothing more than holding it in a normal fashion of use, I have had the top half of the plastic case break, just by holding it on the edge, and I suspect that the home button nub is also a weak spot.
On the plus side: the cover is a piece of genius.
My Mother has an Ipad 1, with a defender around it, and that case, in my opinion totally lives up to the defender reputation, whereas the Ipad 2 case does not. And even though the Ipad 1 case was significantly heavier, and was probably one of the things that the engineers at otterbox was concerned with, unfortunately at the cost of the reputation and my future consideration of any of their products in the future.