I'm really looking forward to this book. It seems like the perfect thing for a developer like me. Usually I just buy a template from ThemeForest and extensively modify it but I'd really like to start from a blank page one day.
You're right though about practice. That topic is on my outline.
IMHO if you've just started out on a startup - its better to be a designer because you can do customer devleopment without touching a line of code but by having a design which shows the customer exactly what to expect.
After you get a bunch of people begging you to build, then you build.