Zooming is really buggy for me in Sketch. Sometimes I just fly around the canvas, and I haven't figured out a good way to recenter like double clicking the hand tool in illustrator.
I figured it out myself that this is buggy, but if you work with it everyday I am confident with it now. I also figuread out that the scrolling over the canvas is (a bit) buggy, too. But I didn't care about it anymore, because I use SPACE+DRAG.