I'm using a bowgun, and while it seems to take more effort I'm enjoying it much more than the melee weapons. If you pay attention to elemental damages you deal a little extra that way. I think the bowgun offers a lot of flexibility, both in combat, and in preparation. Since you can bring so many different types of ammo with you, its easy to adapt to the situation. If you plan ahead you can figure out which ammo types will be the most useful, crag ammo for the barroth to knock is mud armour off, pellet shots for the great jaggi to kill the crowd, and so on and so forth.
I feel much safer 40 ft away from the monster, while my friends bat at it with swords. Its also a great team asset, if you shoot team mates you can unstun them, knock mud of them, and if you have healing shots heal them.
I'm not having a terrible amount of trouble with it in single player, its just a slow and steady sort of thing.