Looking at notebookcheck (personally my go to source for laptop reviews), looks like the display brightness is decent for outdoor usage at about 320nits which is fair though the backlight evenness can be abit better. Outdoor better get 250+ nits, or 300nits min if possible. Normally laptops with cheaper TN panels may go around the low 200s. 400 nits or so are pretty uncommon so this display is decent if you compare the entire spectrum.
The ROG ZEPHYRUS (GX501) doesn't use muxless graphics switching (NVidia Optimus) so the iGPU is pretty much disabled.
Optimus has its own issues on Windows 10, e.g.
diagonal screen tearing for a long time (usage specific). So at their ROG gamer targeted audience, I think its a fair tradeoff to not implement optimus.
On their Witcher 3 Ultra FHD test they averaged a 68W power consumption the GX501's battery runtime to be ~44mins with the 50WHr battery. 50WHr isn't a lot for a HQ (45W TDP) processor and 1080 MAX-Q (90-110W TDP).
For people looking at longer battery runtimes for web browsing, office document processing the Zenbook and ASUSPRO might be a better pick but for hopping power bricks in a lan party of some sort, the GX501 battery is sufficient. Fair tradeoffs, good pick for their target audience, sleek form factor.