The Eizo white paper regarding this issue is quite easy to understand!
Glossy screens have upsides as well as downsides. Upsides include the fact that they generally look better, give the impression of better quality, colors look more vivid and there is more contrast.
Downsides include reflections, eyestrain and the fact that the screen may be more fragile (which is an important issue to me, especially for a laptop. I don't know how Apple new screens behave in that regard).
The is little difference between the two kind of screens "in performance in colorspace and grayscale rendering" if you take away external factors, at least according to Eizo.
According to the same company, glossy screens are appropriate for watching still and moving images but not as appropriate for internet browsing, business applications and editing images, if only because of the reflection / eyestrain issue.
Central to this reflection / eyestrain issue is the issue of AR coating which we do not seem to have heard much about yet.
To sum up, I think it boils down to what you want to use it for:
-Doing serious editing on a laptop (with a glossy or matte screen) which is not connected to a proper external screen is not a good idea to start with in my view for reasons which include screen size and bit depth (you may also have speed issues, storage issues, etc.).
-Extensively editing or working on images on a laptop with a glossy screen is an even worse idea for the reasons mentioned above.
-However, I am not dismissing a laptop with a glossy screen for imaging, since I mostly use laptops for the following: downloading images on location, doing some primary basic work in the field, showing off images and making presentations. A glossy screen may actually have the advantage for this kind of use, I will give it a try.
However, if you want or need to use it mainly for serious editing or cataloging work requiring concentration for extended periods and don't want to or can't use an external screen for doing so, you may be better off with something else.