Sure, I don't think it's possible to not lose detail and/or not fudge the original art a bit with a smoothing shader. But I think it's better about it than SuperEagle, HQx or other XBR shaders. I still use crt-easymode-halation as my default shader for most cores, but I think the new XBR is a neat alternate.Here's the problem though, it messes with the art direction and makes everything look rounded, including assets that aren't supposed to be rounded and smooth. Look at the bricks on the platform in the Mario picture, for instance. These shouldn't be smoothed out like that. I don't think the designer would want them to look so rounded.
So, i'd say it still loses detail.