Not sure how good it is - I think it probably has some useful info in it but its also info you can probably find on the internet or figure out using common sense. I would say a good rule of thumb if you are waitlisted is:
1) Find out the schools official stance on wait listers sending updates - if they dont want updates there isnt much you can do.
2) Find out if the school will provide feedback on general weaknesses/areas of concern in your app.
3) Write a letter addressing those weaknesses and restating your intent to enroll if offered acceptance - show them some love.
4) If they give you specifics, work to correct them and stay in touch every 2-3 weeks with a letter, and e-mail, or even a phonecall if you have a contact in the office.
5) Be ready to wait it out, because it seems like the rounds that come after you have been waitlisted get preferred treatment - you will probably hear something after the deposit deadline if spaces open up.
6) Dont overdue it - make sure you send relevant updates - promotions, improved scores, updated transcripts etc.