As much as it pains me,I must say this episode stinks. Worse yet,this is a 2-part episode,which makes it all the worse.
As others before me have pointed-out,the main story behind this episode is not very plausible. The guest character is not particularly likable,and there is not much chemistry between him and anyone else. It is implied that this character is a saintly lover of nature that is living a 'Waldon pond' type of life. Which may indeed be the case. The thing is,the man is an old crabass and is very abrasive and annoying. Dragging this weak story out over 2 episodes is a strange anomaly for this usually awesome show. As much as I hate to even say it,this has to be the worst 2-part episode in the series. By all means watch it and see what you think,if you are skeptical of my opinion.