There are many moments in this movie that felt very authentic to the experience of playing an RPG. I don't really give a shit if it "wouldn't work in 5E." If anything, it was a pleasant surprise whenever I saw something that is in 5E. But leave it to a bunch of pedantic, joyless nerds to dwell on the accuracy of rules. This movie understood the far more important thing to get right: what it's like to play an adventure with your friends. Everyone brought a delicately-crafted snowflake PC to the table with some backstory prepared, maybe didn't read up on all the class features they have, sometimes forgot the magic items they got, created stupid running jokes throughout the campaign, and were doing their best to say badass one-liners and funny quips despite being a bunch of nerds sitting around someone's parents' dinner table.
In the first half of the movie, a criticism in the back of my head was, "this is a very mid D&D campaign." The Forgotten Realms remains a garbage setting, and this movie does nothing to redeem it. The DM definitely came up in the modern, story-focused tradition of running the game in "scenes" that they've strung together with some excuse plot which the players are asked not to depart from. The PCs are neither cliche nor are they creative. They are the exact sort of forgettable class+race+tragic backstory combos that most first-time D&D players come up with. "Tiefling druid raised by elves whose motivation is some vague thing about wanting to protect nature, but is still pliable enough that they'll work in the DM's campaign without much friction." A big part of me wished that it was more like, y'know, a good campaign. Maybe even a great campaign.
In the second half, I began to appreciate the value in it being, like, an extremely generic campaign instead. Because that's what most people who play D&D are going to experience. They'll run some shittily-made WotC 5E module set in the Sword Coast with a forgettable villain, listen to (and forget) tons of lore and backstory that both does-and-doesn't matter, and then, every once in awhile... they get to actually play. They're thrown into a scene with a weird and tricky problem to overcome, and they start trying to solve it. They debate, make plans, leverage their resources, make some hilariously stupid suggestions, and eventually succeed through a combination of lucky die rolls and genuinely good ideas, the kind that only D&D players can come up with.
Asking whether or not the movie is good is a bit useless. I have a far more interesting question.
Every now and then someone asks about what movies and shows "feel the most like D&D." The most commonly-agreed upon answers usually aren't high fantasy works like Lord of the Rings or Willow. Rather, they're the ones about characters going on quests, using their noggins to solve problems, usually working as a team, and overall just seem to be tackling challenges that feel like the sorts of thing a DM would cook up to entertain their friends for the evening. Tremors, The Expanse, Jim Henson's Labyrinth, The Mandalorian, Big Trouble in Little China, those sorts of things.
My one thing I was hoping for more than anything else is if this movie would be a fitting answer to that question. "What movies feel the most like playing D&D?" And it actually was.
Overall I rate it a 1/10, because it only had one dwarf in it.