I'm really loving the hunting horn. I used to be a hammer use but I see no reason not to use the hunting horn. It does nearly as much damage (in fact, the starting hunting horn does more damage than the starting hammer), has some useful support skills, and most importantly, it has a seemingly much better move set than the hammer. Am I missing something here? The hunting horn seems too good. Not that I'm complaining. ;D
I switched too after all the fun I had with the demo HH, been doing very well with it so far.
As for downsides - it doesn't have the raw power of the golfswing, none of its moves are anywhere close. Its 'super pound' is not as strong as the hammer's, although near as I can tell the hitbox is the same. Hammer's got higher KO values too but the HH makes up for it by being able to hit faster and more consistently thanks to its moveset. Which is actually kinda more important due to how KO works. You can offset the lower damage if you get a horn with attack up buffs as well. One disadvantage is that you burn through weapon sharpness much faster than a hammer, which was really annoying until I made this Lagi horn which has lots of green sharpness.
I also like that ALL of the HH's moves have their own uses, including the recital attacks. The upswing is a little awkward but extremely good for KOing. Even the stupid hilt stab is good for getting a note out quickly. Learning the songs is a lot easier than I expected too.
I'll probably switch around to different weapons eventually but for now I'd be quite comfortable taking this online. Whenever Capcom decides to let me.