So, unless you adjust the brightness and contrast appropriately and have a hi-DPI laptop, e-ink will come on top for reading. There's also the convenience in holding the reader vs using the laptop to read.
So cannot really compare it to a common laptop. To actually compare like to like, compare an e-ink reader with a hi-dpi ("retina") tablet, with the brightness/contrast configured appropriately.
Agreed about the ergonomics: it's more comfortable to hold a kindle than a laptop. However, I'm not sure I could replicate the experience with a tablet: I'd have to lower brightness a lot, increase contrast, and shine a light on it, at which point LCDs stop being comfortable to read.
However, in my experience, resolution matters too. I increased the font-size on my monitor and saw a clear impact on readability.