Safari's JS support is pretty good, but CSS is wonky and various other things (like how cookies are handled) are different than all the other major browsers. So

Safari's JS support is pretty good, but CSS is wonky and various other things (like how cookies are handled) are different than all the other major browsers. So it will break on shit devs may not expect. Obviously that's the fault of the devs (IE10/11 are worse, but we make stuff work there too!), no argument there. But it is becoming a pretty niche browser, and yes, it DOES break a lot of stuff. No, it's not broken on Facebook or your favorite news site, but every time I bring it out for a test drive I find a couple of broken things in various smaller web apps that work everywhere else. So while I don't think it should be that way, it tends to be a pretty brittle experience.