This is an excellent chapter in Doctor Who history.  There was a lot riding on The Power of the Daleks - it was a huge gamble replacing the Doctor's actor, but I think Sylvester McCoy does a great job at establishing himself as a distinct and new version of the character.  It cannot be understated how big of a deal and how much this would influence the franchise going forward.  I think that's pretty cool overall, especially with how confident it feels production was of McCoy's take on the character.

The Doctor spends a lot of time playing his recorder here and acts seemingly like a buffoon.  Yet there's an inner strength and fire.  You can still connect all this to the First Doctor, but the performance is entirely a new creation.  It all works really well, especially with Ben and Polly understandably freaking out about the regeneration and not really knowing what has happened to the Doctor.  In a lot of ways, this would be the blueprint for all post-regeneration stories to come.  It's very impressive overall.

It helps that the actual story with the Daleks is great overall.  Sure, the whole idea of Daleks pretending to be good is outright a trope into itself at this point, but the idea was fresh and new here.  It definitely helps this story was executed in a memorable way, with lots of characters from the colony of Vulcan really standing out and leaving a strong impression on me.  On the whole, this is a highlight in the Second Doctor era. With only a few episodes feeling like they stall out the pacing a bit, it's very nearly a perfect viewing experience I would definitely recommend.  This is especially true with the animated reconstruction, which really feels like it restores the original experience of these episode as best as possible with existing footage and material.