@jrista (if he or she is still here)
As a long time Opera user, since version 8 or so, I too feel the pain of Opera's reinvention, despite my still using it on both my work and home machines as my primary browser. HOWEVER, your approach to the problem, the sturm and drang and "OMG YOU SUCKK!!!!", is only going to antagonise people and presumably lead to a ban.
I also want to take issue with some of your comments regarding the supposedly saintly nature of version 12.
12 was a good browser - however it was NOT perfect. While it had many features that internet users wanted, many of them were lacking in features and functionality. True, flexible password management, for instance, didn't come along until Opera finally allowed true Extensions. It was the same for ad-blocking. M2 was decent as a basic mail client but I had the strong impression that managing the mailbox file, with its thousands of archived messages, was leading to performance issues across the entire browser, most notably opening and closing. And last but not least, BitTorrent functionality was so basic compared to full-blown clients it was pitiful.
You talk a lot about Bookmarks. Frankly, I'm glad they're gone. I had hundreds of them, going back about a decade, making them a nightmare to manage and keep current. I was relying on 3rd party tools to verify broken links but the work of managing them was a bit of a drag. Honestly, I was glad they went away. I'm using the speed dial and not really missing having the bloat of an unwieldy library. I get that for those that liked them their loss is a bitter pill to swallow, but I see it as a niche concern. Mainstream users either won't care or will simply adjust as I have.
The lack of site compatibility may not have directly been Opera's fault in most cases, although I firmly believe their ethos of trying to adjust the web to suit their approach was a nigh-religious motivation that ignored the practicalities of browsing the web. That might have been okay were it not for the fact that this devotion came at the at the expense of the experience for every Opera user. This, more than any other problem with Opera, was a serious problem that needed something as drastic as this engine change to happen. Like many others I presumed most of the functionality would transfer across to version 15, and was fairly horrified when 15 emerged as basically a skin over a Chrome shell, but it was IMMEDIATELY apparent how much smoother the experience of visiting sites - the primary purpose of a browser - had become. And it has freed the developers from having to provide endless hacks and workarounds for sites that clearly didn't see any need to kowtow to Opera's tiny percentage of the market, presumably caused by Opera's problems browsing the most popular sites: the ultimate catch-22 situation.
Several versions later we're still awaiting the return of many beloved features. Some may never return. MyOpera is gone. The brilliant, free Fastmail based mail service is gone. Opera is now something very different from the browser and ethos of old, and it easy to be dismayed at the loss of something truly unique, even angry. Personally, I'm hoping customisable mouse gestures return soon so I can once again open closed pages with a quick flick upwards. It angers me that I have to rely on a process for this vital function far slower than I'm used to. I also really liked the expandable, groupable tab thumbnails. But ranting and raving and shouting and insulting will not, WILL NEVER, get you what you want, and nor should it.
Your choice is simple. Live with the situation, and work WITH Opera to help bring missed features back. Or move on and spare the rest of us your rudeness. Best of luck with what you decide.