Gfail
When Gmail implemented its new design, my initial response was fairly positive; I liked the cleaner, simpler look (though it still has a long way to go in terms of aesthetics). My main quibble was that the icons seemed like a step backwards from the text labels. As icons go, they’re reasonably clear, but they still require a momentary pause to “translate” them, something that wasn’t the case with the text labels. Not the best design decision, then, but a relatively minor concern.*
But after a week or so of using the new Gmail, I noticed something odd: I kept hitting the arrow for “Back to Inbox” after writing a reply, instead of hitting “Send.” I assumed this was completely my fault, because the Back to Inbox arrow is orthogonal, clearly indicating a “back” or “return” action—an arrow denoting “Send” would presumably be straight. So it must have been some hiccup in my poor old brain, right?
Not exactly, and in fact, it’s not really my fault. I didn’t notice it until I was writing a rather long reply, but the row of icons, which is anchored to the top of the message, covers up the Send, Save Now, and Discard buttons once you scroll down in your reply, so that you can’t see them without scrolling to either the top or the bottom of the message you’re writing. 
So one natural response is to hit whatever button is in the position you expect the send button to be in. My brain was saying something like “I see that icon, and I’m not taking the nanosecond needed to process what it represents; it’s where the ‘Send’ button is supposed to be, so I’ll just hit it and the message will be sent.” Oops.
Now that I’ve recognized the problem, I’m consciously scrolling up to find the actual Send button, but I wonder why, when I’m writing a message, I see less likely actions like Back to Inbox persistently but have to hunt for the primary ones like Send. Kind of a Gfail, I think.
*The metaphor-mixing is also slightly puzzling—some actions have icons and some have text labels, and though that doesn’t trigger a cognitive collapse or anything, it does, again, give just that nanosecond of pause. I’m sure it would have been difficult to come up with an icon for, say, Discard (as opposed to Delete), but using icons for some actions and not others is a bit of an odd decision.
