Well, the game it's done. There is a lot to say, but I'm too lazy and tired to develop a better wall of text and besides, I'm in the RPG Codex so there's nothing new I could contribute in a place full of veterans. I will share some obvious words though.
What I'm about to say has been said a lot but it's impressive that Jon van Caneghem almost alone pull off this game, without removing credit to the other guys that helped to materialize it of course. Also, part of its design reminds me of Wizardry and Ultima, almost as if were a combination of the two.
I liked that the core of the game's design is the adventuring, then comes the quests and character progression that are very linked in between and helps retroactively to develop the adventure, in simple words adventuring gives you quests to do, those quests gives you more new locations to find and experience to your characters, so after that you can keep exploring more hazardous areas. Something so simple and still manages to accomplish a game with a lot of content and hours of play.
The level design is very memorable and fun to map, the overworld match very well the map that comes with the manual and like newtmonkey said in a post it feels like you explore a massive world instead of just a combination of 16x16 dungeons with trees and mountain layouts.
I did not like combat that much, I ended up with the impression that it was just about throwing the best of you in each encounter and then rest to not die in the next one. Also, most of the time I encountered multiple enemies and almost all of them were able to attack in hand to hand, making useless a lot of the spell repertory, because I really needed spells with wider range of impact (a lot of the spells only afected 1 enemy), specially fighting against spell caster monsters. At the end the solution was farm experience and gold in the wyvern's peaks (It wasn't boring though and felt very rewarding, I have to give some points to that). The bribe, retreat and surrender thing was a very interesting mechanic, but it turned out a bit useless in the middle game (was a miracle if worked so I stoped trying at some point). The only tactical aspect I found interesting in contrast to other RPGs I played from the era is that you don't give the orders of all members at once, that gives the oportunity to react a little bit in the middle of the actions, change positions during combat also can be an advantage of sort if only the first 2 are in hand to hand.
Character creation was a bit bland, but very easy and quick (the reroll feature being the main reason), now I think after playing almost the whole game that I made a mistake, that I didn't make an archer, a second character with Lightining bolt would have made things a bit easier plus the fighting ability. In the end like the manual said, having each one of the classes in the party was the safest bet in the long run.
The overall experience was great though, I enjoyed it and learned from it, I let some things unfinished to add replayability. Also I could have found the Inner Sanctum before recuing the King, It was mandatory to finish the game?
