After having been a happy Opera user for about 15 years I decided to switch to Google Chrome.
It was no easy decision because I think I'll miss the clean and keyboard centric interface of the old opera. But on the other hand since the release of opera 15 the whole thing was just close to unuseable.
I don't mind the decision to use the chrome rendering engine, in fact I think that may be one of the better decisions. But to cut out nearly all the features that made opera attractive was just too much to bear.
I still clinged to opera 12 until a while ago but luckily after finding some extensions for chrome I can get somewhat close to the old opera workflow:
This one is available for all browsers and quite cool. It blocks all those annoying trackers.
I didn't need that one in the old opera because banner blocking was a core functionality. But it works good in chrome.
This one brings a lot of useful keyboard shortcuts. Especially switching tabs for- and backward is extremely handy. It may be too much like vim for most people but I find it quite useful. In fact this extension is the one that allowed me to switch to chrome without breaking my workflow.
The awesome opera developer tools (Dragonfly) are gone for good. I will miss them but the chrome developers tools are useable although not a match for dragonfly.