Ive read till Vol 6 and here is my take on Hell Mode LN.
I personally enjoyed the first two novels a lot more than i expected, the build up felt good and it took time to give a nice climax in the second volume.
The power system of the world felt a little basic to me, but the MC's class is very interesting and was fun to see how it turned out after every skill up.
Maybe since the story is focused on the MC's perspective, I didn't feel too connected with a lot of characters starting from vol 3 onwards and didn't notice any much character growth or stuff with many characters including the MC.
I personally felt the volumes from 4 didn't have much kick in them, and I felt bored during several chapters and even skipped some bonus and side stories which I generally like very much.
Coming to the art, it was simply.... Very bad. Except for a few volume covers like 1, 5 and 6, rest were bad and all the insert illustrations were plain or downright bad imo.
Overall it was a nice read but I feel it's getting dragged on a bit, since even at Vol 6 it didn't go much into the enemies perspective and I feel like the plot will just repeat itself regarding its fights with future enemies.