The high concept, and possibly one that might have inspired Mr Moore's second LoEG volume, is that Sherlock Holmes is caught up in the War of the Worlds, by way of the "Crystal Egg" from Wells' oeuvre, with aid from Conan Doyle's Professor Challenger. What comes out of it is, as another reviewer points out, a pretty uneventful story. Holmes and Challenger spend a lot of time staring into the Crystal Egg, and running around the countryside in the manner of the narrator of Wells' original tale, but very little is added to make it more flavoursome. There is the attempt to make the science of Wells' story more palatable by suggesting the Martians weren't from Mars, because as modern day readers know, there is no life on Mars (or is there?)... but that isn't really enough. Then there's the use of Holmes and Challenger to fill in some backstory from Wells' tome, though within the text Wells' tale is considered a fiction of real events and treated in a slightly derogatory manner. And again, I need more.
Part of the issue, no doubt, is that the novel is actually made up of what were three short stories, and so there is some repetition of past events that would have made sense when the stories were being served up in magazines some months apart.
Another thing is that while I don't think the Wellmans wholly miss the mark in the way they write Holmes and Challenger, it's clear that Challenger is favoured, as he gets a meatier role in the action, and their version of Holmes is very Basil Rathbone. You can hear Jeremy Brett saying the lines, but this Holmes is not so quirky. And Watson is drawn as a slightly buffoonish, very proper Victorian gentleman, again a version of Watson of yesteryear. But then this was written back in the 70s, I think.
The other slight problem with an otherwise handsome little paperback is that there is a preponderance of typographical errors (just let me go back and spellcheck that...). Not a huge amount, but they are stark when they appear.
I didn't dislike the book. It was a pleasant way of passing the time, and the Holmes fanatic liked the little touches of mention Holmes' North Country background and the suggestions of who Mrs Hudson was and why Holmes became a beekeeper in the Sussex Downs. But it doesn't send me to the same heights as the Nicholas Meyer books.