Disadvantages of flex layouts?

Answer 1

(after reading the stackoverflow thread)
Well so, even if the question posted on stackoverflow was about advantages of flex, answers were suggested some more or less outdated support disadvantages: question and answers were posted around 3/4 years ago, and in that time, lacks of flex implementation in browser have been widely fill-in (even if, as usually, microsoft ie/edge delay the support: ie10 implementation follow old rules using -ms- prefixed version of the properties name, and support only start with ie11: unfortunally, ie users are also quite long to upgrade their browsers versions)...

Answer 2

From my point of view (I will read the stackoverflow thread linked by @Elizabeth only after, to avoid to be influenced ^^):
Main disadvantages of flex layouts (slowly but surely reducing) is the still few lacks of support (but todays it's mainly about old browsers/devices versions)...
Secondary disavandage is that it require some learning implication, because it's not very obvious (at least when you have a long background in use of old default box model from Html), but it deserve widely to be study as its powerful reveal itself when you start to understand its logic (and almost its related new css keywords) ;P
Last one, always accoring to me, is it could have some features implementations lacks/bugs, according to the different browsers/platform, and it could get some headhache when mixed with others layout behaviours (but it's more or less the case of almost any feature of Html/Css)...
I have focussed myself on the disadvantages, but I think it have very much more advantage than disadvantages: complex layouts becomes quite easy, fast and efficient to build when you start to acquire some experience about it :) That's not totally surprising, as Flex was developped on the lacks of Html Box model in layout building to fill in the gaps ^^
(I will now go reading the stackoverflow thread, even I just realized than it's about advantages rather than disadvantages :P)