is the Tenth Doctor a coward? The obvious answer to this is of course not. Every version of the Doctor has risked life and limb for the sake of both those he knows about and complete strangers. But a look at this season reveals a startling amount of evidence to the contrary: rather than fight a foe he can clearly dispatch, he puts the lives of a town at risk with his attempt to wait for the enemy to die on its own. Rather than attempt to defeat a clearly murderous group of enemies, he gives in to the idea that they are replacing the minds of bystanders with copies of their own and simply aims to make those copies less murderous. And of course the most questioned point of the season, when the Doctor attempts a Luke Skywalker style redemption plot with an unrepentant murderer of hundreds of millions- trillions if you take into account the classic show.
Ultimately, the Doctor's willingness to risk the health of the many for the sake of the few indicates an important change in this season: rather than goodness or determination, this season's Doctor is characterized by tiredness. He's weary of the wrath and the destruction. His statement that "I lose it all and they always survive" is more than a line for the "Daleks in Manhattan"- in certain ways it's the thesis that this season is based on. The Doctor is trying to get as far from the ruthlessness that characterized Sylvester McCoy's tenure as possible, though as "Family of Blood" indicates, it's never far from him.
At the end of Series 2, the Doctor saw his companion and lover off into a parallel universe as two armies invaded the Earth: one an alternate version of a force that was defeated in that era of time, and the other a force left over from a fleet that the Doctor had made great sacrifices to defeat. The aftermath of this leads into the series 3 opener, “Runaway Bride”, in which the Doctor faces and destroys another ancient enemy of his people, with a ruthlessness that resulted in the titular bride- next season's companion- becoming cautious enough of the Doctor to decline his offer to travel with him. This apparently struck a chord with the Doctor- as I described above, he spends the remainder of the season taking ridiculous risks to avoid doing so again.
This season, even more than the last, is a regeneration. The Doctor has a new companion, who hasn't seen the things that Rose has and reacts to them differently. In that regard this season follows many of the same patterns that Series 1 did, except with a Doctor newly confronted by a close personal loss rather than massive trauma. Rather than the Post Traumatic Dress Disorder he experienced in the past, it seems this Doctors psychological state can be more closely defined by clinical Depression. His response to his loss is to cling to everything from his old life: the Daleks, the Master, and even a world in which the Time Lords caused the extinction of the Racknos.
The season plot is pretty subtle compared to what we've seen before. Rather than setting the season up with enemies for a brawl at the end, Series 3 sets up ideals such as forgiveness (leading to the Master spending a year keeping the Doctor from telling him “I forgive you”), and technology that informs the finale, in the form of screwdrivers and fob watches. With some of the themes I discussed in the first paragraph, this is rather bittersweet- an ambitious idea mired in its own concepts.
Martha is both the most intelligent and the wisest companion new Who has had yet, which is probably why she’s made one of the biggest marks of any one-season companion. That, or maybe the fact that she’s a sassy black girl and the best dresser that would travel with Tennant’s Doctor. As a medical doctor, it’s not surprising that she has traits of the 8th Doctor’s companion Grace Holloway- being kissed by the Doctor, having an episode where he’s half human (“Family of Blood”), and falling in love with him (although she denies it at first). Still, watching Martha interact with her family and the Doctor is a blast; she really has a full life waiting for her back home and you can see that every time the TARDIS stops by the 21st century.
The only downside to Martha is that the stories she’s in could really give a shit about her. If you ignore the fact that “Gridlock” and “The Shakespeare Code” carry elements of “End of the World” (as Martha mentions, “ever heard the word ‘rebound’?”) and that she contributes a line at the end of the latter, the only stories that really involve Martha are the two-parters. It’s these episodes that prove her worth as an invaluable companion, however, as in each she fights for the Doctor’s cause- without his help- for weeks or months on end, without exactly being the most popular person around, and passed with shining colors. “Human Nature” and “Last of the Time Lords”, despite both having their problems, really shine in the companion department.
That’s the key to this season, I think. Really great scenes, really great moments; but the episodes as a whole are too flawed to really call great. I love this season for a lot of reasons, but I can’t call it a good one. It’s a season that you have to watch for the characters and for the great moments, but you can’t pay too much attention to the plot or it gets a little disturbing. I still recommend this season, but only if you fall in love with the characters in “Smith and Jones”.