The indestructible smartphone hasn't been made yet, though if rumors that Apple is going to replace glass on its devices with sapphire (the second hardest mineral after diamonds), maybe we'll get there someday. But in the meantime, dropping a smartphone can mean repairs or even a total goner. While we keep calling these things phones, they're really miniature portable computers, and computers aren't exactly known for their shock-resistance; what's surprising is not that they break, but that we've succeeded in making them as durable as they are now.
Anyway, so an insurance company called ProtectCELL deals with this sort of thing, and they've released figures on how likely various smartphones are to require repairs or replacement. It turns out that Apple's iPhone is quite a bit less likely to need either than its competitors: 46% less likely to need a replacement than owners of other smartphones, and 11% less likely to need a repair. The data should be fairly representative since ProtectCell has over 2 million protection plans sold.
It does seem like iPhone are more highly targeted by thieves (something that might go down as fingerprint sensors become more widespread on all models), though, but that's not a durability problem. In fact, from anecdotal evidence, I would say that Apple products tend to have much longer useful lives than the average, which is a good thing.