There's a distinct "fanfilm" feel to The Sontaran Experiment, in part, no doubt, due to the setting of the story and the way it was shot. Like most fan films, this story takes place in deserted countryside, and is shot on videotape. There's also a distinct lack of incidental music for the first part of Episode One, and without the presence of the TARDIS, any fanfilm budget would not have to stretch to cover the production of that iconic prop.
All these elements lend a rather endearing feel to this episode. Tom Baker gets some great scenes with his Galsec captors, and, with his collarbone still in tact, he's still upwardly mobile. Sarah and Harry continue their lovely antagonistic relationship, too. I adore Elisabeth Sladen's playfulness in the scene where she runs up to The Doctor, who is too busy repairing the transmat beacon to notice her. Harry is quickly making me realize I'm going to miss him when he leaves soon, too.
When the Sontaran, Styre, finally appears, it's worth the supposed surprise (although the reveal of the Sontaran without his helmet is the same as in the Sontarans' first appearance in The Time Warrior) just to see how Sarah reacts to him.