I walked part of the VDLP earlier this year and researched many blogs and the UK Confraternity guide and Alison Raju's guide before leaving. All were informative, but in my opinion the best is the guide produced by the Amigos del
Camino de Santiago de Sevilla, as noted by others in reply to this question. It is spiral bound so that when opened out, the map of the stage is shown and below it is the description. Information on the map shows route, profile, degree of difficulty, towns/cities, rivers, adjacent roads and landmarks. On the other page is the description of the route, albergues and other accommodation, bars, pharmacies, ATM's, etc. The book shows the 37 stages to Santiago and the alternative route to Astorga.
The cost is 10 euros when bought in Seville, and it is printed on good quality paper. It is not as detailed as
John Brierley's guides, and includes only the information directly about the VDLP, without history, preparation, spirituality etc.
The problem is obtaining a copy before your arrival in Seville, as the Amigos do not accept Visa/MasterCard, and only a bank draft from overseas (which is normally very expensive). I bought my copy in Seville from Triana Backpackers and I emailed them beforehand to let them know that I wanted a copy. They also have Credentials. I believe another source is Hotel Simon and one or two bookshops, and the Amigos. But the Amigos office is only open for limited hours in the evenings on Mondays, Tuesdays, Wednesdays and Thursdays.
I found that on the VDLP there are many new albergues, and the number of pilgrims was much greater than I had read about, mainly German and French, and each day tended to be a race to get to an albergue to get a bed. Many walkers start at 5 am., both to get a bed and to avoid walking during the heat of the day. This was in April, which is probably a popular month to commence.
Send me a message if you wish to know more. David