I find it works pretty well on my 8.9" tablet so would guess it'd be even better on a 10" or larger tab. On my tablet while I can read okay without zooming I find it easier to zoom in by double tapping the screen to read and double tapping again to get the full page again. This may or may not be enough zoom for you, if it's not you can also pinch to zoom (unpinch?) to get things even larger. It's mostly seamless, but there are occasions on my tablet where it takes a bit extra for the page to render in full resolution (also when zooming way in).
As to if it takes away from "real" magazine reading I'm not quite sure how to answer as I've never been a huge magazine reader nor seen it as any kind of particular "experience" (other than sometimes getting ink on my hands
) I often just read specific articles of interest and move on not reading the rest of a given issue. There are others here who probably use Zinio a lot more than I do so hopefully you'll get some more experienced answers about this.