After a full days use on my T-Mobile LG G6, it's definitely not as buttery as my Pixel but performance is good enough for an Android device running last year's silicon. You can tell the software isn't optimized for the SD821 like it is on the Pixel. The Pixel is by far the smoothest phone I've ever used.
So far the only thing that bugs me is the uneven LCD screen, the bottom half is warmer than the top which triggers my OCD like crazy and I see it every time on a white background. Brings back memories of my OnePlus One days where I had to exchange 4 different times to get a half way decent screen.
I'm getting really good battery life so far which is a good sign and it charges way faster than my Pixel it seems. Camera so far has been pretty meh... I took a few night pictures and they come out better on my Pixel.
So far, Pixel to me is still the king, I'll most likely return this thing and try the Galaxy S8. If that doesn't blow me away, I'm hanging onto my Pixel until the next gen version.