What do collector's want to see in a Wehrpass or Soldbuch?

[Anthony N]

I am a medal collector, Wermacht medals, not political etc.
I am looking to buy a Wehrpass or Soldbuch as it will compliment the growing collection nicely, but i know practically nothing about them.
What as a collector do you like to see in a Soldbuch or Wehrpass?
Many thanks, Ant.