This was, out of the 11 or so full commentaries I've read on Jude (and who knows how many 1 page commentaries I read), my favorite one. It's concise, delves into the meaning of the text, and makes it very clear how this epistle applies to our lives today in addition to a much needed attention given to Jude. Both as a historical figure, great saint of the Church, and as an epistle given to the whole Church for our instruction, correction, and training us in righteousness (2 Tim 3.16).
And it talks about mermaids, sex robots, and a man who went from being a member of the KKK to pastoring an Asian-American church by the transformative power of God's grace. This book, for anyone wanting to study Jude, should be at the top of their list.