It certainly isn't completely out of date... Most of what changed in 2.5 was the UI, all the tools are there, only a couple changed names, and you can search for them using the space bar. So no, this is still a very good resource, especially if you jump to #blender channel in freenode IRC, if you can't find something that changed in 2.5. It also has improved alot from 5 years ago, in my opinion, but sure, there is still alot to be done.