Unsurprisingly, Who spoilers follow.
My initial thought upon watching The Waters of Mars (over a three hour period on iPlayer for reasons not worth elaborating upon) was that it was easily the best of the (I think) six specials so far. Granted, that's not exactly a huge accomplishment (Voyage of the Damned is arguably the worst thing Davies has produced since he launched the new show, and that really is a difficult record to claim); perhaps it would be fairer to just say that WoM (as I shall henceforth refer to it, recalling the terrible ice-lolly stick jokes of my youth ) was, all things considered, really rather good.
One of the things I've noted before about Davies is that for all of his wearying shit-talk about totally ignoring "ming-mongs" (by which he means anyone on-line who has a reason for not liking the show), successive iterations of his Who scripts do seem to actually take note of the criticism levelled at him. WoM carries on this noble tradition of incremental improvement in several ways. There is a notable reduction in attempting to be overly cute, the gadget droid aside , and whilst whinging emo-Doctor is still present and correct, the central premise of the story (essentially a retread of The Fires of Pompeii with less insanity to distract from the core concept) is strong enough to make his moping seem pretty reasonable. There aren't any of the massive lapses in basic character or plot logic that threatened to shake Planet of the Dead apart (restricting the story to one location for almost the whole run-time doubtless helped here). The hapless victims of the Martian water are genuinely chilling (the first possession scene ranks amongst the very best Who scenes, old or new), though in fairness monster-creation isn't something Davies gets wrong too often. Most importantly, though: the Doctor no longer saves the day within thirty seconds in a storm of shouty babbling and unnecessary gurning.
Nah, I'm kidding. Of course the Doctor saves the day within thirty seconds in a storm of shouty babbling and unnecessary gurning. This time, though, there's an actual point to it all. People - well, smart people - have been complaining since Last of the Timelords, if not earlier, that the frequent comparisons between the Doctor and Jesus Christ (or some other messianic figure) were ludicrous and overblown, even within the context of a show that relies on ludicrous and overblown to get anywhere at all. The constant reminders that the Doctor was the most noble, tortured, good-hearted heroic soul ever were entirely redundant in a show in which he's already the (near-immortal genius) protagonist, and they came across, much like Davies insistence that Rose was the best companion imaginable, as a desperate attempt to tell the audience that the characters were worthy of appreciation. Rather than do anything as prosaic or difficult as demonstrating their worth, script after script would simply have various characters insist that the Doctor and Rose were perfect.
This constant obsession with hammering home the God-like wonders of the main characters was also used to cover up the appalling clumsiness with which many stories were wrapped up. Granted, 50 minutes isn't much time to piece together entire stories that, unlike most TV shows, were generally started almost entirely from scratch (once again, three cheers for the psychic paper, and any use of the sonic-screwdriver that advances the story rather than replaces it), but RTD chose to fill up umpteen minutes of every episode with the Doctor sulking and Rose being a pain in the arse, so he can damn well suck it up. I'm not sure which came first, the obsession with portraying the Doctor as a humanist God, or the lazy resolving of plots with a flick of the screwdriver and a pointless catch-phrase, but certainly the two rapidly fed into each other. I've said before that one of my biggest problems with Tennant-era Who (I don't think this was true of Eccleston's tenure) is that crises were no longer solved by the Doctor actively struggling against them, but were instead dealt with simply by dint of the Doctor showing up (last night's special was an obvious example, but see also Gridlock or The Doctor's Daughter); the entire thrust of the narrative development reduced to ensuring the Doctor got to the right place to work his magic. Everyone's favourite Time Lord was a teleport device away from total omnipotence. 
Last night, we finally got to witness the effect that all this epic win has had on the Doctor; he's started believing his own bullshit.
With that one move, I can forgive a lot of what has gone before. I don't intend to give Davies too much credit for it (this, after all, is a man who spent two years thinking a story arc meant repeating the same phrase ad infinitum, so my opinion of his forward planning skills are not high), but at least now each ludicrous eleventh hour save can be considered a link in a chain, leading to the Doctor concluding (not entirely unreasonably, quite frankly) that the fact he always wins means he can play far faster and looser with the rules than he has up until now. After all, what's the point in worrying about consequences when any result you don't like can be dodged in less time than it takes to make a cup of tea? So what if Adelaide had survived, and history hadn't gone according to plan? The Doctor could handle it. So what if the Reapers showed up to eat her face (along with reality)? A couple of seconds of running around to horribly out-of-place pseudo-techno and the Doctor will be able to wish them all away. It is, at once, a hideous development for our hero, and the logical zenith of the rebellious, arrogant streak he's demonstrated since the very beginning.
It's also absolutely the most perfect note to herald this particular Doctor's end.
 What do you do with a wombat?
 Today's lesson for Davies: an irritating character does not become less annoying just because another character confesses that they are annoying. Mind you, I don't think it's ever occurred to Davies that one can invoke any given reaction in the audience without being told to feel it by at least one character.
 Well, he has the TARDIS, but then he can't use that, because he's "locked into events", or some such. I shouldn't complain about that one, because without that hand-wave the whole show would become entirely impossible. Of course, he could easily get a different teleport device, like Jack's, for instance, which the Doctor has no problem making use of. Something else that infuriates me about the current incarnation of Who is the constant technobabble arms-race. Instead of setting down basic rules, or even limiting the Doctor's abilities (the latter being the preferable alternative of the two), the show simply lets him do whatever he wants with that damned sonic screwdriver up until a story would immediately collapse if he could use it at all. Hence the ridiculous invention of the "deadlock seal", a method for defeating sonic screwdrivers which villains can use on everything from car doors to Maitre D androids, just so long as it forces the Doctor to come up with an alternative fix that can play out over the course of 30 seconds.