I have to chuckle at people. They want thin and light. They also don't mind giving Apple a 50%+ margin on something they buy from them, which incidentally is pretty dumb. Almost as dumb as camping out in front of an Apple store for three days so you can be among the first to own the newest fad.
What it means for you is that your brand new iPhone's case is made of a material that's cheap for Apple to use. It's pretty, but it will bend, and where the buttons are and the material has been weakened (a lot) by cutting those holes it will bend very easily. It's a classic case of form over function.
So if you stick it in your back pocket (not a good idea in the first place) you might find that it has more of a curve coming out than it did going in. That, by the way, can break the screen too, or detach it from the base, which is arguably just as bad if not worse, especially if you try to unbend it.
This is what you get when you reward companies that build things with form (e.g. "pretty", "thin", etc) before function (e.g. will it survive everyday use, does it have good RF performance, etc.) Apple could have chosen a material with considerably better strength (e.g. magnesium or titanium alloy), but it would have been more expensive (and cut into their margin), or they could have used more material (at the cost of thickness and/or weight).
Instead, they put out a $600+ device that is quite easy to damage in what many people consider to be ordinary daily use. One of the reasons I have contempt for Apple is that they have always been known for intentional planned obsolescence in an attempt to force you back into their store for another bite of your wallet.
However, this little ditty may be a bit too much of curve even for them, particularly given the extraordinarily high asking price attached. Will the morons who pray at the alter of Apple ever wise up? I doubt it. This is economic Darwinism at its best, and a fool and their money are soon parted. But then again, who needs any money when they live at home in their parents' basement?
That's what you get for being an iFanboi and buying iCrap!
Full disclosure and a silver lining: We have made a boat load of money investing in Apple stock over the past 10 years (starting around $72/share and before the splits). As long as their are fools who will buy this stuff, I'm more than willing to profit from their ignorance.