Though as a fan I am glad Seven got a proper send-off, I nevertheless agree with those who say it was a mistake to launch a new version of Doctor Who with one actor only to have him turn into another after 20 minutes!

For the viewer not previously familiar with Doctor Who, it must have been weird and confusing (and not in a good way!).

Better to start, as RTD did, with the new Doctor already present. It keeps the information the new viewers have to process to a minimum.