Loved this story! It was very interesting to see the Sensorites' mental capabilities. Reminds me of a whacky conspiracy theory video I watched on YouTube once about an alien found in a crashed UFO who could only speak through mind and could also read minds, and I've always found that idea quite unnerving since. I certainly enjoyed the Sensorites as a species, personally.
I hear lots of talk of this serial being quite long-winded and boring in the middle. Personally, it flew by for me. I found it very entertaining throughout. I wasn't really expecting the Sensorites to be a violent species, so when we did see those few scenes of the 'bad' Sensorites using force I was pleasantly surprised and found it very entertaining indeed.
Only criticisms would be that there's not enough Barbra in this story, and also this serial is absolutely rife with people stumbling over their lines, isn't it? I mean it wasn't just Bill in this one, it was every single one of them at one point or another...
These are little nitpicks though and honestly had no impact on my enjoyment of the story.
I'd give this one a solid 5 out of 5. One of my favourites so far!