[Burt]

I think Donna will be fantastic as an companion. She's different to Rose and Martha, which is what you really need. The problem (for me) with Martha, was she was too like Rose. Started off shocked...learned to grow into traveling... the whole 'in love' with the Doctor thing. Looking back at the earlier Doctors, they had a bit more different companions. Leela - pre-historic girl, Turlough - Alien, Romana - Timelady, Jamie - From the past, Zoe - from the future...
I like how she both was and wasn't afraid of the Doctor, and even how she was a little bit shallow.
I rewatched 'The Runaway Bride' yesterday. I'd forgotten how much humor was in that episode, and most of it... from Donna.
I think it's also great that a past 'companion' will be returning (In a way) instead of meeting and whisking away someone in the same episode.
Saying all that, this will probley go balls up, be the worst series so far, finish off Doctor Who forever and destroy the BBC.
However, I remain blissfully optimistic!