I've been doing mindfulness-related stuff -- meditation, yoga -- for a long time, but I'd never read specifically about mindfulness. If you've done yoga and meditation before, there's very little new in it, but it's a helpful reminder to slow down and really taste, touch, smell, hear, see things. It's an easy read -- as befits an introductory, practical guide -- and easy to absorb, with lots of practical advice and careful explanation of what you're "meant" to do.
Since it's practical, it's very unfluffy about it -- if you feel like mindfulness/meditation/etc is kind of a hippy thing to do, this probably won't dissuade you at first glance, but it doesn't make it sound mystical or anything like that.