Jon Pertwee gets a pretty good sendoff in the Planet of Spiders, Likely not as good as he deserved but still worth your time.
We see the Doctor FINALLY reach the blue planet that he has been talking about for two seasons. Yet it is a planet with problems, specifically it is being ruled by spiders who are enslaving the humans.
The plot turns involving the meditation center, the other timelord and Mike Yates are interesting, as is the final regeneration scene, I did take exception to one bit of the plot.
It seem strange that the Doctor knowing that the Queen Spider is about to doom herself, while trying to become the most powerful creature in the world would put himself into such danger to try to talk her out of it. If he succeeds she will continue to be a menace. This seems to forshadow Tom Baker more than the quite practical Jon Pertwee. The psycological factor is played well, but I still don't buy it.
Pertwee was a long running doctor, he would give way to the longest running (and in my opinion the best) doctor, and sometimes that gives him short shift in comparison. This is unfair. Pertwee was a class act, a class actor, and a class doctor.