This story in itself is very good, fairly simplistic and padded with capture/escape/capture routines but the production design and (first time) location filming are excellent. Although the plot is straight forward there are a couple of twists and character reveals that keep the interest. The editing in the live action segments is clever and I didn't realise until the documentary that William Russell was on holiday for two episodes. (His scenes were pre-recoreded on film). Check out "The Book of Lists" for a full list of cast holidays/illnesses and how they were 'explained' in the corresponding episodes. After all they couldn't just replace an actor with another when they had chicken-pox (I think it was) for one week. Oh, what ? See "The Mind Robber"?
The animation is a mixed bag I'm afraid. Firstly, I am more than happy it's here. I want to see as complete a story as possible and as I watched I was already imagining how The Tenth Planet pt 4 might look or Power of the Daleks. I even thought about even animating existing episodes using the original soundtracks the we could see Wirrn that don't bounce on their bums.
The problem lies here. Unless you have the money (I'm not going to say 'animating skills' cos this is still animation under a tight budget)of Disney or Dreamworks, the realism is going to be limited. I don't mind this. The Invasion episodes, Scream of the Shalka, Shada, Infinite Quest and Dreamland all have their pros and cons as animated Who but all are watchable. Here it is the same.
Firstly, I found a dip in sound quality in these animated episodes and that knocked me before any animation. After a couple of minutes however, I acclimatised and it was no longer a problem.
Where my gripe starts is the changing character likenesses between shots (hence "the Regenerating Doctor"). It's not just a case of, for example, the Doctor not looking like William Hartnell.... It's that sometimes he does (usally head on) and then from another angle he looks like someone else (with a fat chin). Susan suffers with this also (different hairstyles) as do most of the other cast members. It is a little jarring. The quick cuts also stand out at times but they do help the episodes flow. The animation is sometimes simple eyebrow raising contrasted with what I believe were rotoscoped actions which become very fluid. The other thing the animation emphasises more than live action is how limited the range of sets are. (Yes it's due to budget) One set in the prison, one set in a big(ish) room for the most of the two episodes. That's NOT the fault of the animation in this case but just emphasises the budget limits of the show. It is redeemed with a trip to Television Studios (see the documentary)for the final part.
So, in summary, a good episode, well acted and nicely restored. An informative documentary. The animation is mixed, never bad, sometimes very impressive, but a bit inconsistent. I'm not going to compare it to other animated Who because that boils down to your own taste and suspension of belief. Loved the spiders walking on the web tho.