I read this back-to-back with Monteiro's second book You're My Favorite Client which is, of course, the wrong way round, but in the end it doesn't really matter, though I have to admit I liked Design is a Job better. Marginally. They're both pretty great.
Why? I think because even though I don't have more than an iota of art execution skills, I do consider myself a Designer. Sure, it's arrogant. Every real designer-y Designer right now is actually close to punching the screen reading this, but the fact is I do think of myself as someone who Design things whether they be ideas, solutions, capabilities, projects, applications or even, most recently organizations and teams.