If you're programming a (2-dimensional graphics) isometric game, there isn't much reason to go beyond DX7 anyway. But yes, I would suspect that much of the stuff in the book would still be useful with DX8/9/10, just the DirectX-specific stuff would have to be looked up online or something.

That book is definitely still relevant. It basically consists of a large Win32 and DirectX tutorial followed by a large section that goes over Isometric algorithms and code. The first section is not relevant, but the second part is great. For some reason, pretty much all game programming books written back then had large DX tutorials strapped to them, and included "DirectX" in the title. I think this was a marketing ploy.

I have found this book useful and have never touched Win32 or DirectX.