Thanks!
It took me nearly a week plus
a lot of time to create characters. So I'm not sure it was awfully fast. ;)
The combat was rather straightforward and IWD is all about combat, so I didn't have much problem there. Although maybe core rules difficulty with max hp on level up isn't particularly challenging, I don't know. I didn't learn much about DnD combat. I didn't really have to counter magic with whatever you counter it, I just focused casters. I still don't really know what kind of weapons are good against which opponents.
I put a portion of my cleric/thief skill points into Detect Illusion. It was useful.
Once. Thief's trap detection and opening locks were helpful, although I've stepped into many traps before they were detected anyway. As for cleric... healing in combat was something I didn't do much, it was somewhat inconvenient. Maybe it's just me, but their healing was simply weak. And he wasn't at all more useful at dealing with undead than other party members.
The sorceress did a lot of AoE damage and crowd control, and was pretty good with a sling, with a good survivability. As for picking spells on level up... that frequently resulted to googling suggestions, just like during character creation.
In general:
Paladin was tanking and doing damage, as expected. Kensai was a bit squishy. The same for cleric/thief (because of thief armor limitations I suppose). Archer was doing their pincushion things all right with occasional melee action. Sorcerer's good with fiery-expody things, highly recommended. Bard was mostly standing behind and singing, thanks to high lore they were useful at identifying gear.