Here is Lizo from Newsround weekly review of Doctor Who, I would also like to congratulate Lizo on getting promoted but I hope he still writes his wonderful reviews, here is the one for The Poison Sky:
It's not looking good. The skies over the world are filling with toxic gas, the evil Martha clone is helping to put the Sontarans' plan into operation, and the Doctor can't work out what the aliens are really up to.
Can Donna stop the Sontarans?There's only one person who can save the day. But is Donna up to it?
The second half of this two-part adventure rattles along at great pace. And is pretty much action packed from start to finish.
Better still, after helping the Doctor over the last few episodes Donna gets the chance to see if she can do things on her own.
The Doctor's got big problems too, in this episode. Not only is he trying to stop the war-like Sontarans, but he's also doing his best to hold UNIT back from launching what could be a disastrous attack on the aliens.
The Doctor's got BIG problemsThis story's anti-war message works well, with the Doctor leading by example as he demonstrates that violence should only ever be used when there's absolutely no alternative.
But it's not all grim fighting, there are some lovely moments of humour, especially for fans who've been watching the series since it came back three years ago.
Some two-part stories promise much in the first-half, but fail to deliver in the second. But the concluding part of this adventure is one that doesn't disappoint.
It's simply a great story, with the Doctor once more taking on deadly opponents armed only with his wits.
And you know that that means the Sontarans don't stand a chance!