This was my first time listening to this one, and I liked it pretty well. It was a good (re)introduction to the Doctors. Of the three sections, I enjoyed Six and Five's the most. In fact, I've been consistently surprised at how much I enjoy Colin Baker's performances for BF, in general.
I figured out the Big Bad pretty early--the title gives it away, really. ;) That being said, alternating between the Doctors kept the story from sinking into the audio version of padding, so I was pleased.
And I'm a sucker for multi-Doctor interaction, so the last part was a lot of fun. :)
Overall, a good, solid story that, while not absolutely stellar in writing, still did a good job of reintroducing the show to an audio format.