Shada is a Tom Baker Doctor Who serial that never completed filming because there was a strike. What is on this DVD is the footage that they did film linked up with Tom Baker giving narration for the footage that was not filmed. While this is helpful and makes for an overall enjoyable experience, at times it feels like Tom Baker is telling you a story rather than acting in it. With that said the story is enjoyable.
Another version of Shada is on disc 1, but to get to that version you'll have to put the DVD in the computer and play the flash file. Paul McGann who played The Doctor in Doctor Who: The Movie is The Doctor in this version of Shada instead of Tom Baker. It isn't live action like the Tom Baker version, but instead animated. It's a shame that this isn't playable on a regular DVD or Blu-Ray player, but at least it's included.
On disc 2 is a nice documentary called More Than 30 Years In The T.A.R.D.I.S. This documentary features those that acted in the Doctor Who serials as well as the two Doctor Who movies Hammer Studios put out, and it gives you a nice history of how things were on and off the screen and the cultural impact Doctor Who had.
In a way I think of this set as more of a big bonus feature set than a complete Doctor Who story. You're not going to get the full story of the Tom Baker version of Shada since it doesn't exist, between this version with linking narration and the flash video version of Paul McGann's Shada you get as complete of a version as you can get. As long as you understand that and if you want to complete your Doctor Who collection, I would recommend getting this.