I'm in the middle of Blood Dragon at the moment. The campaign may be short, but I don't know that yet, because I'm basically ignoring it. The meat of the game is pure FC3 colonization, reskinned. New island, new bases (now garrisons), new enemies (now robots), new animals (old ones mutated or robotized), and new weapons--kinda sort of. The vehicles are there too, though less varied. The steps for becoming a full badass may be simplified, but the development path is basically the same. Killing and scavenging earn you points for level up, as well as specific perks, like being able to buy weapons attachments.
This character development and systematic island conquest is what I liked best about FC3. Here it feels very much like a mod of the full game, and that's fine. The good thing for all concerned is that you need not own FC3 to play it, it's cheap, and there's a long game for whoever prefers exploration and development over a linear dash to the finish line. Good for us, and good for the dev team, who are seeing some worthy financial success.
The one new enemy is the blood dragon, who is an over-the-top mighty beast that can kill you with a laser glare. I mostly avoid them. Fortunately, they can't see well, and I can sneak past them, or throw cyber-hearts (like throwing rocks) which make them run to eat them like a puppy chases a stick. You can use them to clear out bases for you too. It's hilarious.