The late F.F. Bruce, a professor at the University of Manchester and author of many excellent New Testament commentaries, has produced an excellent work in his commentary on the Gospel of John. This book is intended to be read by lay members of the church, so there isn't an awful lot of Greek, nor is there jargon. In fact, he does such a good job avoiding such issues, that he "makes it look easy," the mark of one whose scholarly and writing skills have been finely honed.
The format is simple: Bruce translates a few verses of John, then offers an explanation (sometimes only a paragraph, sometimes a page or two). He comments on the historical/cultural context, Messianic expectations, the other three Gospel accounts, and other interesting literary or theological issues. One walks away knowing he has a better handle on John.
This reader appreciates F.F. Bruce's conservative theology. He argues that the disciple John wrote this Gospel (and effectively supports this argument), he does not speculate get into "development of the text" issues, and he places a heavy focus on Jesus, his work, and his teachings. Many excellent scholars are so focused on text-criticism issues, that they blind themselves to Christ himself.
Also of note is Bruce's treatment of the (controversial) passage concerning the woman caught in adultery. Added to the end as an appendix, he argues that while Johnnine authorship is in doubt, the passage is authentic Gospel and treats it quite fairly. In all, a very good commenary that I would recommend to laity and those who want a good introduction to John.