I am no great Whostorian to remember all the details of the seasons I have watched already, but I think this is one of the shortest of the serials thus far, weighing in at only two episodes. This serial leads reasonably neatly on from the previous on, where the Doctor and partners teleport down to Earth to find it fairly deserted, but with some remnants of humanity hanging on. While these "remnants" take an instant distrust to the Doctor, another, much greater danger lurks in the background with nefarious goals for the planet.
Interesting to come to this serial off the back of Ark in Space, because in terms of shooting it seems to be the total opposite of that serial. While Ark was wholly inside a few sets with no externals, The Sontaran Experiment appears to be entirely filmed outdoors on the moors somewhere. I am not entirely sure that the location does sell the idea of an Earth bereft of most of its human life, but it is effective for the space it offers (and maybe I am used to such scenarios just being crumbling cities – which I guess would be long since crumbled in this scenario). Much like Ark though, the serial benefits from a limited number of characters and a short number of episodes, so there is really no padded here at all. I am not sure if this is deliberate or not, but certainly in season 12 so far it does seem different from other seasons where you could easily imagine the three serials being padded out to more episodes. Anyway, the brevity of this serial does actually help, because it throws us into a scene and moves us through it quite quickly. I guess it could have been spread out a bit, but it works pretty well with the time it has, and has a good pace. There is not a huge amount of detail, but it does have some nice moments; again, similar to Ark, there are some unsettling moments – here the terror- visions of Sarah Jane are quite creepy; as indeed is the whole idea of torture and experiments. It is another solid serial in this new season.
The special effects and sets are limited and have dated but wisely there is not too much of them. I am not sure what the costume department were thinking by putting Sarah Jane into some hideous garish creation – perhaps it was a mix of costume and also hi-vis outfit to highlight where she is in case she got lost? In terms of performances Baker is solid again, judging his Doctor just right between too serious and too comedic. Sladen is good despite her costume and mostly being in peril here. Marter is starting to grow on me a little; although still not a big fan of his very 1970's 'old girl' character, although this is not his fault. The supporting cast are good, although I thought the Sontaran in Time Warrior had a bit more space to have a character and presence than Lindsay did here.
Overall, a tight and engaging little serial that is not strong enough to be a classic, but it does its job in the time it needs, and it does it pretty well – which after too many 3-part serials delivered as 6-part serials, that is no bad thing at all.