One of my least favourite things about the Third Doctor era is the Third Doctor, so it was with some hope that I turned to this Past Doctor Adventure set in his absence. (I had also enjoyed McIntee's Second Doctor / future Master story, The Dark Path.) My hope was largely justified. The Brigadier and the Master spark rather well, and there are lots of gleeful continuity moments (including a surprise reference to Delta and the Bannermen). Ian and Barbara take a while to bed into the UNIT environment, though, and the treatment of Barbara in particular isn't terribly satisfactory; Ian as temporary Scientific Adviser is almost Liz Shaw to the Master as Doctor.
The actual plot is basically decent but important details get drowned out by continuity squee (though of course most readers will be concentrating on the squee). McIntee has apparently said he would have liked the villainous Marianne to be played by Jacqueline Pearce, and I can see that. A fun experiment with the format.