It's fine.  Better than some of the older annuals I've read, which is nice.  Some pretty memorable prose setting up the atmosphere and nice, striking visuals accompany this short story, but the story itself is a pretty basic thing.  It does have the feel of a Fourth Doctor and Romana story, it just doesn't really go anywhere, introducing a sentient being of energy and quickly defeating it without much fanfare or difficulty implied on the Doctor's part.  Kind of boring, but at least boring with a little bit of style to it.