Well, in case you managed to ignore the news in 2013 (a lot of people did), it uses Chrome's Blink-engine now, instead of the Presto-engine which they previously developed.
So, it's very much identical to Chrome for the most part.
In fact, you can use Chrome plugins for Opera. It's basically Chrome with a slightly different feature set.
I used it for a while when Chrome's UI was broken on high DPI screens. I loved it; it did basically everything Chrome did with a bit more polish, and as a bonus all of my Chrome extensions were compatible. Of course, I didn't have that old pre-Blink baseline to compare it to, so you might be disappointed coming back to it. I went back to Chrome after the Qihoo buyout.
I was a long time Chrome user, and was driven to Opera as Chrome got slower and slower each year. Now I find Chrome basically unusable, in that pages take far too long to become scrollable, and suffer from other kinds of unresponsiveness. Opera has been perfect. Always fast and responsive.