Yeah, I'm playing at Adventurer difficulty. I thought it might be a little on the easy side, but it totally isn't at all. Most of the regular enemies aren't too bad, unless I let myself get surrounded, but the bosses really pull out all the stops.
Here's my party composition:
-1 melee expert
-1 melee expert with a dash of magic
-1 bow expert [who was basically worthless until she got some healing spells]
-1 magic expert [by far the most useful member of my party since spells always connect and do much more raw damage than physical attacks, at least in my experience]
I'd almost rather have a party of mages, but they would get roasted in a close-quarters fights due to their low armor rating.