I got the nanotexture on my current work M4 MBP—it doesn't completely eliminate reflected light, but it diffuses it a lot. If I were in a dark room with a light source positioned perfectly to reflect off my screen in my face, I would probably still have trouble with it, but in general I don't need to reposition the screen to avoid glare nearly as much.
I would say it's worth the extra, what, $200 or so? on the price of the M4 MBP. If it were much more expensive, I would be less sure.
It’s often much more than $200 as the base models can be had for huge discounts, like $450 off retail, but the second you check the nano texture option, you lose the discount and you tack on the extra $200. So it’s often closer to $700 in some cases.