Lord John and the Hand of the Devils is one short story and two novellas.
My biggest question after reading this: why not publish all the Lord John stories in order?
I know they can be read out of order, but it makes more sense when you read them in order because of the relationships that develop among Lord John and other characters.
The Hellfire Club seemed too large of an idea to me for a short story. It ended rather abruptly, but then this was Gabaldon's first Lord John story.
The Succubus was my favorite. There is some detail about the beginning of the relationship between Lord John and Stephan von Namtzen. I will confess, in reading Brotherhood of the Blade, I didn't understand their connection; it had seemed random to me, as if Lord John had some really great gaydar, but now it is more clear. I simply read out of order!
The Haunted Soldier wasn't as great as Succubus, but it was ok, probably on par with the Private Matter.
I am not crazy about these mystery stories. Gabaldon shine when she gets time to write in detail and make intricate plot connections.
I just wasn't so interested in these. Not to say that they were a waste of my time, I still enjoyed them. Lord John stories seem lacking compared to Outlander. Like a bit more empty.