This is a great introductory book on Sikhism and it is clear from his respect and engaging tone that Owen Cole has a fond familiarity with the Sikh community. The front cover of the book cites its goal as "in-depth understanding", and I agree that if you were to read the book from cover to cover and make the effort to take the information in and go and do your own research, you would definitely reach that objective. It covers all the major points and adds some anecdotes here and there which help make the book more accessible by applying it to particular scenarios. It is also well balanced and honest, for example in explaining the caste system (which has no place in Sikhi) he does admit that it is still influential in Panjabi culture and therefore is an issue for some families.
As for criticisms, I did notice that occasionally a prominent Sikh figure was mentioned without explaining who they were until a few chapters on, which isn't very helpful, especially since the page isn't referenced. I also noticed that sometimes transliterations of Panjabi words (like jura) would be used without explaining them until later, which could easily have been avoided and would have greatly enhanced the ease of digesting the information.
Another small observation is that Cole seems a little 'old fashioned' in his explorations of Sikh culture...whilst the author gets two thumbs up for mentioning gora/goree sikhs, he doesn't give so much as a page to reference Yogi Bhajan who brought Sikhism to America and totally re-envigorated the faith. It is exactly this kind of information that leaves the book lagging somewhat behind and giving it a slightly 'factual' feel rather than giving a sweeping view of the way Sikhism is practiced across the world today.
Overall though, it's the best introduction I have read and would thoroughly recommend it as a very comprehensive starting point.