Subjectively, I'd say at those settings the WebP versions look slightly worse, though they don't suffer from the blocking artifacts native to JPEG. For the images I serve on my sites, a few KB here and there aren't going to make a huge difference, and I'd rather avoid the hassle of serving content that isn't universally supported.
Zoom in (400%) on the cap of the yellow hat. The lines of the cap are muddied under all lossy compressed formats, but surprisingly, plain old cjpeg does so less than the others.
Generally though I find the new formats look better than JPEG.