Lizo, our Doctor Who-obsessed presenter, gives the first of his reviews of the new series.
Find out here what he thought of episode one - Partners in Crime.
The last time we saw The Doctor, he was once more on his own at the end of Voyage of the Damned.
But that hasn't stopped him doing what he does best - investigating mysterious goings on. This time he's looking into a company headed by the sinister Miss Foster called Adipose Industries, which is producing a diet pill that helps people lose weight.
But why is Donna - who decided not to travel with The Doctor at the end of The Runaway Bride - at the company headquarters?
And what will happen when she meets The Doctor again?
This is a pretty good start to the series thanks to a script filled with emotional moments, ranging from incredibly funny to terribly sad.
More importantly Donna turns out to be very different to The Doctor's previous companions, Martha and Rose. But she still shows him that she has what it takes to help him when he most needs it.
For loyal fans who've watched lots of stories over the last three years, there's an extra layer of enjoyment and mystery, with tiny snippets of things mentioned in previous episodes. As well as other things that don't quite seem to make sense...
Add into the mix some of the cutest aliens yet seen on the show, along with some other gobsmacking special effects, and you've got an episode that promises much over the next 13 weeks.
Four out of Five
"I was blown away. Catherine Tate was better than I could ever imagine and Rose's shock return made me scream at the television. The most amazing opening episode I have ever seen. I am hungry for more!"
Ryan, 13, Oxfordshire, England
"When I saw Rose appear at the end I nearly choked on my dinner. My Mum thought I had gone mad when I started screaming!"
Amelia, 12, Cardiff, Wales
"I love Doctor Who, especially the new series with Catherine Tate!"
Katie, 10, London, England
"I love Dr Who but I am disappointed in his new companion. Donna is too old for him, more like his mum. Bring back Rose!"
Chloe, 13, London, England
"It was awesome... not the best ever episode but it was a great start to the series. Donna will be a great companion :)"
Masumah, 13, London, England
"I thought this episode was going to be rubbish but surprisingly it was amazing and Rose made my day!!!"
Ben, 11, Bournemouth, England
"Doctor Who is cool. But the Adipose were rubbish."
James, 11, Durham, England
"Brill! It was funny when they where talking through the windows, it was hilarious! It was sad when Miss Foster wanted to be their nanny and splatted to the floor."
Lewis, 10, Dumfries, Scotland
"Mmmm... I'm not sure. I'm a big fan of Doctor Who but I thought this episode was a bit weird, though I think the rest of the series will be good."
Hannah, 12, Birmingham, England
"Doctor Who is the best. I like David Tennant and Catherine Tate. They are both the best."
Sophie, 13, Wolverhampton
"I love Doctor Who so I loved that episode. I couldn't wait until it started again."
Helena, 9, Thatcham
"When I saw Billie Piper (aka Rose) in the episode, I went into total shock. It was a great first episode and I can't wait for the next one."
Sophie, 14, Burton Latimer
"I think Doctor Who's great. It's really funny and great to watch on a Saturday especially. I cannot wait to the next episode!""
Ellie, 9, Fleet
"I think Doctor Who is a cool Sci-Fi TV show!!!!"
Lewis, 11, Caerphilly
"It was a good episode. I liked it when they met again."
Tavleen, 6, Milton Keynes
"It was amazing! I was so excited when the woman turned around and it was Rose. Donna was really funny!"
Louisa, 12, Oxford
"It was funny when the Doctor and Donna were at the window."
William, 11, Staines
"A great start to a promising looking series. Full of action and humour, simply great. 8/10"
Adam, 11, Ystradgynlais
"I think it is going to be brilliant. Catherine Tate will add more humour to it."
Ruby, 11, Leicester
"I love Doctor Who, it's so well written. I saw Partners In Crime and it was fantastic! I'm so excited about the new series!"
Becca, 13, Wiltshire
"I actually though that it was really a disappointing episode, the fact that they are bringing Rose and Martha back means that they've run out of ideas for storylines."
Aled, 13, Bangor
"When I saw Rose in this episode I was gobsmacked even though I knew she was coming later on in the series!"
Charlotte, 12, Surrey
"Really well done! Strong feisty assistant and mysterious new gadgets! And Rose! Brilliant!"
Nicole, 11, Aberdeen
"I think that it was great, and what's more great is that Donna (Catherine Tate) is back in action with the Doctor."
Crystal, 10, London
"I think that this episode is going to be excellent with his feisty new assistant."
Ethan, 8, Essex, England
"Even though I have not watched it, I think it will be really good."
Sara, 7, Staffordshire, England
"Doctor Who is great because the monsters are just cool. I liked the 2nd series
with Martha Jones in."
Michael, 8, Cheshire, England
"I think that Doctor Who is really good - with David Tennant and Catherine Tate this series of Doctor Who can't fail!"
Mehvish, 9, Lancashire, England
"I love Doctor Who. I can't wait for the new series, I'm counting down the days already. It's great because Doctor Who is another thing that makes the weekend amazing."
Isabelle, 13, County Louth, Ireland
"Doctor Who is the best thing you will ever watch! It is absolutely, positively fabulous."
Cordelia, 10, Ayrshire, Scotland
"David is the best and the new series will be the best it ever could."
Lauren, 13, Tyne and wear, England