John Gardner would probably have been the first to tell you he wasn't in the pantheon of great writers. What he was, however, was a "pro" -- a reliable, no fuss and feathers, author who gave you a good story and didn't waste your time. When you finished, you'd have enjoyed 250-350 pages of being entertained.
"No Human Enemy" is another solid entry in the Suzie Mountford saga, meant to be the penultimate chapter in a six-book series. John Gardner died before finishing the series, but fortunately "No Human Enemy" can be taken as the end because it ties up the major romantic through-story and leaves no other threads hanging.
As for the book itself, it hooks your interest at the start and keeps you turning the pages until the finish. In other words, typical Gardner.
Still, you can't help but be disappointed that the series didn't get its last chapter, and that we have lost a leading "pro" author.