I was impressed with the guest cast, but somewhat disappointed in how they were under-utilized.
Andre Braugher was very good, as always. We will be seeing a lot more of him this season, as House continues to work through his issues. He represents the only character on the show who can hold his own against House, and is obviously his equal in diagnostic skills.
OTOH, I was very disappointed in how Curtis Armstrong was used. We saw a new side of him, not like the over the top berserker we have seen in Revenge of the Nerds, Risky Business, Moonlighting, etc. However the part he was given could have been played by anyone and was mostly invisible. I wonder if we will be seeing more of him as the season progresses.