I liked this episode so much that I just had to write a review! It is light, and deep, entertaining and emotional. Especially Jensen shines in this one, showing all his range as an actor - a natural in comedic scenes, while academy award level brilliant in the scene where he is starting to lose who he is. In a way this episode is like a mini-movie on its own, and the montage at the end - which I loved - really ties a bow on this excellent "filler" episode. If filler episodes were all like this, we wouldnt dare call them filler episodes...
I find it so strange that some of the best actors live in the world of these type of sci-fi/fantasy shows, and they just fly under the radar never getting recognition for their talent outside of the fanbase. They wonder why Supernatural has so many diehard fans - it is because we get to see some of the best actors and some of the most fun writing out there. We get Al Pacino (just better looking !) and Shane Black for 41 minutes many times over in the year. Though they get no awards, and they dont get all that fame, but they get undying love and appreciation from the fans.