The guide is fantastic and the Airport Extreme Card upgrade took me less than an hour to complete. It wasn't very difficult. Some pointers: read the entire guide before undertaking the project; keep the screws from each step separated in labeled containers; buy a spludger if you don't already have one; keep a tweezer handy for the tiny screws; and take your time separating the keyboard from the computer so as to not crack/break the plastic bezel.
Once they have, you'll be able to view a graph of their reputation gained over time.
Here's a preview of what the graph will look like:
No reputation gained yet.