The biggest problem was how every character was given too much and too little.
Est was given great character growth but with little to no screentime for us the readers to see. He gets kicked, and in the next 2 instances we see h8m, he gets op and then returns to the former party and gets a misunderstanding scene that would make the Rental Girlfriend author happy. The next we see him, he's now full emo and is shown being op and then meeting his former party again. Not even a full chapter later, he gets a new team and suddenly decides to forgive the former party. He gets no buildup nor mention until he's about to show up in front of Daru and crew. Speaking of Daru-
He's literally just a character. One moment he's the laid back old guy who is being friendly and trying to calm down Est while kicking him out, suddenly he's actually a really strong adventurer that none of the other guild npcs talk about and was just farming in a beginner dungeon while drinking his life away, and now his laid back personality becomes one that is quick to anger by a simple insult. Its like the author didn't know which type of person that they wanted Daru to be and decided to make him a new one each chapter. He was given too many characters and not enough time to expand on them.
Athena, despite being named after the Greek Goddess of wisdom, was not really smart. I'll just chalk it up to her being a young and inexperienced adventurer l, which I can use to hate on Daru even more. Her friend got injured one time and she said "welp, time to kick him out." She gets injured and it's treated as "Oh, You just aren't experienced with not using the enchantments." But then apparently she was weaker than Est when he wasn't enchanting her (sword? armor? sword and armor?). So what happens? She gets rewarded by having Daru decide to become the mentor character and help her get stronger.
Mirialia exists. That's about it. I can't say more except for that her character arc is currently what's being focused on and I didn't read the LN or WN. She's safe... for now, but you know who isn't?
Frey. My only complaint was the bet. It just doesn't make sense to bet her virginity unless she was actually hoping to lose, which makes no sense since she was supposed to be a prideful being. Other than that chekhov's gun that was used for "fanservice," her character is pretty simple and, sadly, the best written.
TL
R for others who were reading comments
The entire party suffers from not having enough backstory for us to really care about except sympathy points for Est and Frey being a new member not associated with the rest. This manga itself is a collection of great ideas with horrible execution, and while being bad, it's not as bad as others that I've seen, but it has no idea what identity it wants to have