I've noticed a lot of, relatively minor, inconsistencies since switching to flex-box. It definitely takes a while to adjust to them and iron them all out. At this point, now that it's working, I've mostly forgotten what the quirks were.<p>But I agree with the author, there was a lot of trial and error moments to get the layouts we wanted working across browsers, and even then there were some unexplainable quirks that we just couldn't figure out and had to back away from and take different approaches.<p>IE, as usual, seemed to have the biggest issues. I recall that one issue was it didn't behave consistently if you left out the flex-basis value. So instead of `flex: 1`, you would find that fully specifying `flex: 1 1 auto` would behave more consistently in certain situations.