Let me be clear:
A capacitive button has no place on a phone, and the people who are pushing it into the marketplace are over-fetishizing visual design to the detriment of the overall experience. Which is a bit of a pet peeve of mine.
What's Capacitive, Again?
A button with no physical hardware, so it makes no distinction between "I pressed that button because I meant to" and "my finger brushed against the face of the phone, sending me to another screen against my will, sometimes even losing data in the process."
The Capacitive Button's Sad Track Record
I have never seen a capacitive button that's better than a physical one. The G4 Cube infamously tried a capitative power button. I personally witnessed dozens of people say "ooo, a Cube ... it feels so nice ..." as their finger brushed against the button, making the computer shut off.
The third generation iPod (what I refer to as the worst iPod of all time) tried capacitive buttons. This made it impossible to use in your pocket. Not just harder, where things were a few clicks away - actually impossible. As your fingers searched around for the appropriate button, they'd brush against the wrong button, fast-forwarding your track to the next song when you really wanted to turn up the volume.
The result was a design that required me to stop, take the iPod out of my pocket, look at the screen, carefully press the button I wanted, then verify that it worked onscreen, since there was no physical click to provide feedback.
Right around the time Apple discovered how useless capacitive buttons are, many smartphone makers are trying their hand at it. There is a reason iPods, iPhones, and iPads have a single, obvious button ... and it's not that Apple is unfamiliar with capacitive technology.
"But It's Pretty!"
Whatever, dude.
"It's In Right Now"
So was Fabio.
User Intention is Sacred
I get scared when people talk about software or hardware assuming what a user is trying to do. This is an area where you need to consider the 10% of the time it fails, not the joy of the 90% (at best) where it might get it right. The capacitive button is even worse because it removes all nuance - if my finger gets anywhere near the button, whoosh, the phone's making an executive decision on my behalf.
Website links require you to click them. Imagine if they worked just by your cursor rolling over them. Suddenly the page would feel like a minefield, because you'd have to chaperone your cursor carefully to your next action for fear of mousing over the wrong thing. That's what smartphones are doing to us now.
"I Don't Have That Problem"
Do some user testing. Watch how often people playing swipe games like Fruit Ninja accidentally graze the buttons and get whisked out of the game. Compare a toddler's use of a capacitive button device to an iPhone. I've done some informal research with my kid and his friends - there's no contest.
And So
Capacitive buttons make for a worse experience in all cases, even if they make the phone look sleeker. The capacitive button cult must be stopped.
