Halfway through Dishonored 2 ATM and loving it - feels a bit slicker and more polished than the original which I also adored. The game had a lot of issues with motion sickness in the past which prevented me from experiencing it.
Difficult to say what it'd be like as a newcomer as I'm quite familiar with the world and characters.
The gameplay is slick as ever and I'd argue more fun than the first, but there's not much of a tutorial at the beginning - a fair amount of assumed knowledge is implied.
I'd say for the best experience, you should still play the first one as there's plenty of throwback in the second installment's story. They're very much married in that respect.
If you're curious, the first one must be quite cheap these days and well worth it in my opinion.