This is one of the best how-to books out there for artists of any and all stripes. It teaches how to pay attention to things and draw recognizable renderings of the things around you. Once you start to really see things, drawing them becomes easy - the trick is to pay close attention to details you often take for granted or miss entirely.
After a couple days of work I was able to draw houses, trees, furniture, jewelry, appliances, and a myriad of other things before I was done with chapter one. Nothing I rendered looked fantastic but I could show my drawings to anyone and they could immediately tell what they were. But the real benefit wasn't the end results, but the process of observation. I'd say what I learned most from this book is that 80-90% of any "field drawing" (or drawing what you see, on the fly) is observation and the other 10-20% is putting ink on paper.
The only real problem I have with this book is its implicit structure, and I had to read the whole book before I started using it just so I could record the lessons in the order they were presented. This was important to me because I planned to do every exercise, in order, as the author intended.
Here are the lessons in the book, in the order they are presented in:
Proportion and scale
Construction, tone, and detail exercise
Grid exercises 1 and 2
Frame exercises 1 and 2
Shape exercises 1 and 2
Detail and Pattern
The order makes sense, the lessons are valuable, and the exercises are challenging and fruitful. You have to dig a little to see just how much material is covered in this tiny little book (the table of contents is missing all of the above), but it is well worth the effort. And for the cost of this book, a notebook, and a box of ballpoint pens, you will get the best sketching education ever.
I also have Visual Notes for Architects and Designers, which is not a how-to book like this one but is an expansion on the material presented here. I highly recommend getting both, starting with this one, and doing ALL the exercises. Good luck!