I've found Safari to be much MORE reliable, if for no other reason than playing HTML5 video made Safari crash reliably in Lion, which doesn't happen in Mountain Lion.
Specifically, HTML5 video via the YouTube5 extension was fine. Also, HTML5 video that YouTube and Vimeo voluntarily showed me was fine. HTML5 video on The Escapist was not fine, and would crash somewhere between immediately and 30 seconds in (sometimes, but rarely, longer, but never so long as a minute).
This made AllThingsD especially frustrating to deal with, because they have HTML5 video straight on their front page, and while it doesn't auto play, it would cause the webview process to go into a crash loop until I closed that tab between crashes. I felt especially bad for my laptop (and the web server) when I opened a new tab to AllThingsD and went to get some water and it crashed 15-20 times in a row.
Now? Everything works great. Faster, smoother, less crashy.
Specifically, HTML5 video via the YouTube5 extension was fine. Also, HTML5 video that YouTube and Vimeo voluntarily showed me was fine. HTML5 video on The Escapist was not fine, and would crash somewhere between immediately and 30 seconds in (sometimes, but rarely, longer, but never so long as a minute).
This made AllThingsD especially frustrating to deal with, because they have HTML5 video straight on their front page, and while it doesn't auto play, it would cause the webview process to go into a crash loop until I closed that tab between crashes. I felt especially bad for my laptop (and the web server) when I opened a new tab to AllThingsD and went to get some water and it crashed 15-20 times in a row.
Now? Everything works great. Faster, smoother, less crashy.