It will work fine, great even, if you’re a student or hobbiest. Zero lag in Photoshop, and only a minor reduction in polygon rendering resolution when doing anything large in ZBrush. It’s great paired with my 2017 MBP. Good for working on the road when needed. Though if I just need to draw, I use the iPad apps for that.
But if you intend to work professionally in 3D with Photoshop, Zbrush, and/or another 3D program like Maya or 3DS Max, then you’ll need to get a decently high-spec Windows PC with dual nVidia cards, and an actual Wacom tablet attached. There just isn’t any better option right now, and Apple’s current roadmap of introducing PCIe breakout boxes still isn’t going to cut it for professional work. Both because MacOS’s OpenGL performance is a third or less for the same hardware in Windows, and because these breakout boxes (and the OS) will only support a single full-size 3D card when they’re introduced fully in October. AND they will only work at anywhere near full-speed when plugged into a USB-C/Thunderbolt 3 port. Which excludes every Mac not released this year. AND so far they only work on an external monitor that you plug into the breakout box. Meaning, it’s all a glorified hack meant to get around the fact that Apple doesn’t have a proper modular desktop tower system anymore, and hasn’t paid proper attention to its 3D performance.
Pro work demands pro tools. I love my 3 Macs, but I’ve also just built a PC with dual nVidia 1080ti cards and a 27" Cintique for doing anything 3D-intensive. Besides zero realtime lag in Zbrush and 3DSMax when using large models/scenes, the nVidia cards boost my VRay rendering (a high quality 3rd party production renderer) by 30x. That means my one box can render faster than a rack of 30 PCs that only use the CPU for rendering. No Mac can touch this kind of 3D performance right now.