One of our first worries with the AirPods, even before we'd tried them on, was that they could simply fall out of your ears. We tested this going for a heavy 5km street run, after which we were sweaty and tired, but the AirPods stayed the entire route, never once threatening to bounce out of our ears. We could see how a very sudden impact such as a car braking might cause them to go adrift, but for regular everyday use they're very solid.
Apple rather likes its design notes to stand out, and there's no doubting that this is true of the AirPods. Great if you're walking the fashion runway at Milan, but perhaps a little less desirable late on a Friday night when you're leaving the pub. Even if you're staying in secure areas, they do still also have that slight social awkwardness that has long been associated with Bluetooth earpieces. Maybe Apple can change that over time, but right now it's definitely an issue.
Competing bud earphones come with silicon tips to fit different ear canal sizes, but the AirPods are a one-size-fits-or-falls-out proposition. We didn't have issues with this, but if you typically reach for the largest silicon tips for your earbuds, you might find them a less than optimal fit.
Remember how white iPods used to show every scuff and mark? The AirPods are like that, but with whatever material may collect in your ears. Again, that's a function of any in-ear buds, but the stark glossy white really serves to show it off to its full revolting potential.