This book is worth the money. It is short and concise. I have been reading from it every day in the morning. There is always a good message in every devotional. There are only 84 devotions so it won't take you forever to read.
You get the core of ideas from the institutes in short digestible doses. You get more of a genuine view of Calvin, as opposed to the flavor of it from the pulpit, or the dissection of it in layperson arguments of it.
It doesn't make you an expert in TULIP, but it does make you much more comfortable, confident, and secure with your own personal Calvinistic leanings.