I'm on chromium on amd64 linux (gentoo) primarily, but I've had marginal success on opera mobile on my phone as well.
The quick reply box automatically tries to double-post (but hits the 15-second limit) when I go to submit.
Reply with quote doesn't work at all - I see the little progress circle, but it's literally not doing anything. I'm not sure exactly what multiquote is supposed to do, but all it does is change the button's icon to a check... no change elsewhere.
I'd really appreciate (but I'm probably alone) going back to the old (or nasioc) style behavior - the big quote button goes to the "advanced" page, and the quote button throws you to the advanced page with a quote block. At least make the current behavior work!
If there's any way I can help troubleshoot, let me know - I'm not familiar with vbulletin at all.
This has been an issue just since the changed layout - I can't think of exactly when it showed up.