It's a refreshing change playing with non-optimized single class characters.
In previous games I usually had 4-5 characters with 18/.. str, 18 dex and weapon specialization who could just shoot almost everything before it gets close, now the monsters actually get into melee and my summons don't last very long since I can't shoot the enemies fast enough to keep them alive.
In previous games magic was only for buffing and summoning, spells would only keep the dual- and multiclass fighters from doing damage in physical combat.
Now with fast leveling single class casters it's different, I'm using offensive spells like sunscorch far more often and they do make the difference in the battle.
It's far more satisfying to defeat superior enemies with spells and tactics than just shooting them down.
In spite of being prepared the priests and trolls in the south of DE level 2 was quite hard and the first cold wight ambush when entering level 3 almost made me flee.
The creepy monks weren't as hard as feared. I accidentally triggered the battle in the library and fought my way to the high summoner and finished off the rest without having to free the prisoners.
Currently my party is ready to enter the final level in Dragon's Eye, still without reload. The only character death so far was totally avoidable. My cleric died once in chapter 2. The party was seriously damaged, I couldn't rest on level 3 as long as Presio was still alive, so I went up to level 2, got interrupted by tough lizardmen and used up all spells to win. But instead of going outside to rest safely (I couldn't find the rescued priestess on level 2 any more) I just rested in level 1 and got interrupted by 3 tough lizardmen, they got 3 good attacks within seconds and the cleric with over 20 HP before the battle was gone.
So I had to travel back to Kuldahar and pay 2,200 gold for her to be resurrected, I also bought 2 scrolls of raise dead to have a cheaper way to deal with such situations in the future. The lost money hurts, there are so many useful items (spell scrolls, shimmering sash, rogue's cowl, lucky scimitar,...) I still have to buy for my characters.
I'm considering to wait selling some of the loot until I get to the severed hand, Lehland pays better prices than Conlan.
I gave the "fighter aggressive" script to everyone except the bard (it's a pity there isn't a singing bard script like in IWD2) and have the AI enabled, interrupting for casting and giving special commands. The AI lets the characters attack the nearest enemy every round which can be sometimes annoying when they attack a troll lying on the ground or shoot monsters immune to normal missiles while vulnerable ones are standing behind them. Sometimes the mage ends up near the enemy but luckily he always survived, it's a good thing he has a long range staff and no dagger for melee.
I suspect the winter wolf talisman which grants +10 HP and not the leading position is cursed, I always gave it to a character who's not going to level up soon, when I forgot to take it away from my paladin (who got quite good HP rolls at the 3rd-5th level up) she promptly got only minimum HP at level up.
My plan to make the druid the ultimate animal tank doesn't work perfectly since he got really bad rolls at level up, with 16 con he had only 32 HP (he only got 7 of 35 optional HP) at level 6, luckily he got 2 good level ups afterwards to get a little closer to average, still even the cleric who is a level lower has more.
Without reloads game elements like potions of genius suddenly become useful, you can't afford to fail at scribing important spells.
Since such potions are rare I had to wait until enough scrolls for scribing were assembled, my mage and bard (because of only 15 int he even needs 2 potions) don't know spells of the highest level they can cast. My mage reached level 5 without knowing level 2 or 3 spells.
My bard had her only scroll scribing session before leaving for the temple of the forgotten god, my mage after clearing Dragon's Eye level 1, both are now higher level than the spells they can cast, I've yet to decide how long my party can still survive without them.