Furthermore, the case was still entirely usable - even though the earbud port cover fell off shortly after that, it still works.
So when we bought our iPhone 4 and 4S's, there was no question - Otterbox. We have 3 of the Defender series cases. First I bought mine, but my wife bought one that supposedly reduced emissions, and my daughter bought the Reflex because it splits in half easily so she can dock with her alarm clock. So much for the Pongo case, it broke (and was replaced by the company) 3 times within 6 months, finally she got the Defender. My daughter lost the bottom half of the Reflex case because, well, if she didn't have her head attached...
So they both ended up with the Defender. Since mine was the oldest, it was the first to go. Had to be replaced within 6 months. The other 2, same story.
The way the Otterbox Defender cases are designed, you have a plastic shell that surrounds the phone, covering with clear plastic the accessible portions (screen, Apple logo, camera lens), and providing a mount for the rubber outer impact-resistant cover. However, with the new 4/4S case, they must have changed the rubber material. Certainly for the new form factor, it is more squarish and thus less rounded, providing a thinner material all around. But after a few months of very normal use, the rubber stretched and didn't fit snugly any more. The charger, earphone, and silent switch port covers were very difficult to close, and hung as annoying flaps. The portion covering the home button jutted out, getting caught on everything, and allowing all kinds of dust and dirt underneath. My daughter's cover even had the thin portions of the rubber tear off.
Otterbox does have phenomenal customer service, and replaced the cases with no questions asked (other than purchase date, location, dated photos of the device, etc.). However, after the 1 year warranty has expired on the case, I have spent $50 on a case that is getting worse week by week, and won't be replaced anymore.
So I advise against the Otterbox, at least for the iPhones. From what I have seen, Griffin has a case that is durable, and the iPad cases that I have seen from them are definitely superior.