I was introduced to this book by one of my co-workers. I've been using it (well, my boss' copy of it. I've just ordered my own copy as my contract runs out soon) this year with both my regular classes and my private classes. The activities are well thought out, easy to follow, and generally work well in a classroom setting.
It's easy enough to use. Simply look up, for example, the grammar point that you are teaching and there will be at least 4 activities for you to choose from. The difficulty level varies, but you can usually tweak the activities to work within your classroom.