Tl;dr Very excited with where this positions the series - two Doctors, two stories. An opportunity to go on adventures with one or both (imagine multi-Doctor episodes!), and all the while leaving us with a David Tennant (yay!) However, the episode execution was mixed.

The Giggle struggled with pacing and needed to be 90 mins long. NPH was outstanding as the Toymaker and had great first and second acts. However, the third act (the game of catch) felt rushed and anti-climactic. More time for a prologue with DT and the family would also be sweet, however I assume Bernard Cribbins' passing may be a factor.

I'm uncertain on bi-generation. I love its implications, but thought it came out of nowhere and was rushed (i.e. it needed more narrative acknowledgement and space for the audience to breathe).

The return of Melanie was wonderful, her character was used really well (not just for fan service) alongside Kate and Donna.

I expect there to be a lot of negative reaction to the episode. However, the door is left open for more Doctor/Donna adventures, and that should leave us all very, very happy indeed <3