tl;dr: HOW DOES SAMSUNG STILL MAKE LAGGY SOFTWARE OUT OF THE BOX IN 2017.
Now that I've spent the greater portion of 48 hours with my Galaxy S8 I feel that I've had a reasonable amount of hands on time with it to come to at least an early conclusion of how I feel about it. I'd love it, if I didn't own a Pixel...
My main problem with my S8 is that I also own a Pixel, no matter what processor you throw into the Galaxy, or how much RAM you stuff into it, it just can't compete on a software level until Samsung stops trying to do the most with absolutely everything.
Google's default apps are better than Samsung's, but Samsung doesn't allow me to switch to them without having both instances seeing I can't even disable their factory apps -- my only option is to hide them using a third party launcher and this bandaid approach is underwhelming.
I still believe that Android isn't quite there yet and that's why OEM's such as Samsung try to re-create a lot of the experiences that Google is still working on -- Google having 97 different messaging platforms is a prime example of the lack of cohesion amongst the platform. The real issue is the culture of it's better to build new and be commended than to perfect existing that strives at the Google campus.
The display is fantastic as it is to be expected, it actually makes my iPhone(s) feel as if they're 5 years dated from hardware standpoint. The device feels fantastic in hand, there's no debating it. The camera is also phenomenal as is to be expected.
I really wish Google would bring back Google Edition's to the Play Store, because the S8 with Pixel user experience would be the crème de la crème, unfortunately that isn't plausible in 2017 and we're stuck debating if we want solid hardware or solid software when trying to endure Android as a whole.
I'd still recommend the Pixel over the S8 solely based upon the fact that it's a greater user experience, sure the hardware is mediocre and the Samsung may have a better display, but when it comes to actually getting things done in an enjoyable manner, stutter free, the Pixel is the only real option for Android in it's current state.