Could be. If not as an episode (although it's right up there with the best, IMHO), then at least as a performance. Knowing for quite some time at that point that these would be his last few performances as Doctor Who, Tennant takes the character to new places in this episode - an episode that delves more deeply than any of those that preceded it into what it means to be the Last of the Time Lords, the unbearable burden and the unimaginable power. There is one line in particular, near the end, which I would nominate as the single most exhilarating and at the same time scary moment of the series so far: "The laws of time are mine, and they will OBEY me!". But apart from all that, "Waters Of Mars" is also a riveting, suspenseful stand-alone episode, in the tradition of "The Satan Pit" and "42" (both among my favorites as well), while the enemy - the water - is reminiscent of brilliantly simple ideas such as "the shadows" of "Silence In The Library". The supporting cast is excellent, and when the Doctor steps out of the Tardis at the start you really do feel like you're on Mars! There is one incident near the end, also involving the Tardis, which could have been better timed, but that hardly alters the essence of the story. ***1/2 out of 4.

I like this episode as one that tries to break new grounds in the established Doctor Who series, getting out of the comfort zone. Here we see the Doctor in another episode flying solo and how this affects his judgment without an opposite like Donna. The companion always challenges some critical decisions of the Doctor. The episode ending shows that and how this might affect his future. It is clear special effects and sets have improved a lot through seasons and this episode has a cinema film feeling in its execution. The enemy here is really scary and not always when visible. Acting is excellent and Mr Tennant shows very well Doctor's conflict at the end. Can't wait to watch next episode.

While "Doctor Who" has always had its share of fun, there have been times that it's taken a darker tone. "The Waters of Mars," the second of four specials that mark the end of David Tennant's time as the Tenth Doctor, is such an episode. It's a thrilling, funny, and downright creepy episode. And dare I say it, but I thought it was the darkest episode of the show's history. But not because of the creatures, which the Flood is a downright terrifying monster for the Doctor to face. And it's not the fact that the Doctor has landed at a fixed point in time where historical events must take place, meaning everybody on Mars' Bowie Base One will die. What makes this the darkest episode of all time is none other than the Doctor himself. After having witnessed so much death and destruction, including the death of his own people, the Time Lords, he takes a turn for the dark, believing that he has a right to change historical events, because he is the last of the Time Lords, and decides to take on time itself. He begins by rescuing the three humans not infected by the martian water, including Adelaide Brooke, the base's commander, and a hero. Through some truly ingenious work, he gets them back to Earth on the same day as their death. But now, the Doctor has taken on a dark and malicious arrogance, and believes that there is nothing he cannot do. But Brooke decides to make sure the time line stays right for her, and commits suicide. When she does this, the Doctor realizes that he has gone too far, and believes that his death is at hand. "The Waters of Mars" is definitely the best special created so far: an exciting, character-driven, dark adventure that takes on a more grim storyline that is more suited for "Torchwood," but works here. If there is a complaint I have, it's this, which is more an observation: This episode, with it's dark ending, is definitely not one for young children. But still, it's a terrific episode, and bodes well for the final two episodes of the David Tennant/Russell T. Davies era of "Doctor Who." Grade: A+

What we have here is your basic traditional zombie film plot. The doctor and sundry others are trapped in an environment from which they cannot escape; first one person is infected, then another - the heroes barricade themselves in, anyone touched becomes a zombie - jeez, its just Night Of The Living Dead all over again. This could work if the dialogue was witty and interesting and if the characters were better defined and developed but it isn't and they aren't. There's an interesting attempt at the beginning to create some friction between the captain and her second-in-command but it doesn't go anywhere. When Dr Who is at its best it features intricate, interesting well written plots - this ain't one of them. Fresh writing blood is urgently needed.