I think it's always a good idea to have a simple sidebar, but as long as it's obvious to users that it's not the main focus of the site, you can have whatever. The main problem is that if there's too much users just won't bother reading it, or they'll get confused.
I've noticed that people often just click the first link they find, even if there's loads of actual content left!
I've actually come full circle now, regarding the sidebar, and I'm not including one on my latest redesign -- keeps the focus on the sidebar and makes things less confusing!
To answer your question, from my point of view, it's a very well designed sidebar, everything is clear and nicely spaced and it's the right width so as not to be confused with the content, but there might just be too much information that will either distract people or just get ignored.