Top marks here. This story rivaled Genesis and Power of the Daleks in my book, which is quite high praise. I remember when I first saw this I was so moved by the final ten minutes that I put it on my iPod to keep watching whenever I wanted.
The Dalek's internal conflict was wonderful to watch, especially as it was a losing battle from the beginning. The very essence of what makes a Dalek a Dalek made it impossible to reconcile with itself, resulting in our wonderfully tragic ending.
Though as a Dalek supporter, I have to say that the thought of such a corrupt Dalek running rampant fills me with the ickies.