The Mentalist has a certain charm that lets it stand out from the rest of CBS' dramas that are usually pretty dull, with the exception of a good episode. Most installments of The Mentalist are enjoyable, and this certainly was, but was not one of the season's best.
I think the main problem with this show is that the guest stars are hard to tell apart. Law and Order: Special Victims Unit is the quintessential example of how to book guests. The victims, the suspects, they are all very easy to follow and keep track of, but for The Mentalist it is the exact opposite. I am not saying they need to book big names like SVU does, but get actors who can distinguish themselves, or you are going to confuse a lot of viewers.