I like it so far, I think I'm maybe 2/3rds done (2 of 3 regions cleared, not counting side missions). The story so far is definitely more interesting than FC4 but I'm not sure it lives up to FC3 yet. Though, the kidnapping game mechanic could have been better implemented. I'm really not a fan of how you just pass out and poof, you're in a main story bit regardless of what was going on previously. I think FC4 did boss fights better too, FC5's boss fights so far don't actually involve any fighting for the most part. They are more of a minimally interactive cutscene (as in walking, forwards only) which magically result in the boss's death, somehow, because reasons. It may make more sense upon completion, we'll see.
Combat is pretty much identical to FC3 and 4, so I'm generally happy with it. They've also simplified the crafting system for the better. No more hunting around for 30 minutes for 3 more pairs of bear2341 pelts to craft a lvl1 ammo pouch and then repeating for the drug pouch lvl4 upgrade too or other such nonsense.
Oh, and they finally got rid of all those stupid towers. They even poke fun at it during the tutorial-ish section. I didn't like them in FC3 and they definitely haven't grown on me with time. Now the map reveals itself by just visiting it. It's a much more sensible and natural system.