I thought I was pretty proficient at using vim, but that assumption was completely shattered within a few chapters into the book. Drew Neil, of Vimcasts fame manages to present the dustier corners of Vim in an extremely practical way, complete with real world examples.
If I could give this book 6 stars, I would. If you are interested in becoming more proficient in Vim or are obsessed with Vim, you definitely owe it to yourself to get this book, satisfaction guaranteed.