Watch for some buggy behavior with flexbox in IE11.
"Some buggy behavior" may more or less mean "it completely doesn't work in IE11" (which still has very significant market share) unless you start researching how to write cross-browser flexbox (at which point, welcome to trawling StackOverflow and feeling like you're almost back in the old days of crazy CSS browser hacks).
Watch for some buggy behavior with flexbox in IE11.
"Some buggy behavior" may more or less mean "it completely doesn't work in IE11" (which still has very significant market share) unless you start researching how to write cross-browser flexbox (at which point, welcome to trawling StackOverflow and feeling like you're almost back in the old days of crazy CSS browser hacks).