It's pretty good, albeit much less good since the old XPCOM extension support went away. (My position is that XPCOM compatibility could have been maintained in

It's pretty good, albeit much less good since the old XPCOM extension support went away. (My position is that XPCOM compatibility could have been maintained in a multi-process world through better dynamic object proxying.) But as Mozilla's money dries up, so will Gecko, Servo, and a bunch of other fascinating projects. It's sad. But the web won't stop evolving, so we're going to end up a webkit-only world.