I've played the Hearkenwold mod for about eight hours and I'm not even third level yet, but I'm having fun and wanted to say thanks to Dorateen.
The biggest difference from regular KotC is the open-endedness. Go anywhere, do anything out of order. This has a huge effect on the difficulty vs fun tradeoff. When a combat is too hard, you're not stuck desperately optimizing, you can just go do a different quest. But when it's just hard enough, you get that exact KotC experience of a challenge that makes you learn to use every tool you have to succeed. So if you were daunted by the difficulty of KotC, this is much more approachable.
The nonlinearity of having 100+ locations in a single city is really cool for me. Sure you have to take notes where things are, but that's fun because the notes pay off quickly in finding the quest you want to advance.
The branching dialogue tree is just starting to reveal its coolness to me, as choices I made in one city start showing up with effects in another city. I'm fairly sure every playthrough will show me different options, whether from party skills or doing different quests. I was very excited the first time I had a quest and realized visiting the linguist I'd found earlier would give me more dialogue options.
I highly recommend reading the docs tab of the Nexus mod. There are a few imperfections that Dorateen's "forewarned is forearmed" approach makes much easier to bear. Is it awkward UX that your characters keep standing on the door you wanted to go into or you have to talk to corpses? Sure, but I understand there's a reason for that.
I didn't follow Dorateen's directions about using low-resolution sprites because it was two steps and I like high resolution. But all my high-resolution characters are naked, even after I found armor. Is there a reason or workaround for that?
Based on the 5-5-5 offer I was expecting modules to have a way to pay for them. Is there any way to pay/donate to support this one?
Overall this shows that the KotC2 engine is capable of having exciting, challenging mods created in it. Thanks to BlueSalamander for making the engine and to Dorateen for being an early adopter!