Don't let the title fool you: it describes what happens in the story perfectly! This is a story about a vending machine reincarnation set in a dungeon-fantasy world, and it keeps to its promise whole-heartedly and steadfastly, holding onto the title of greatest vending machine reincarnation fantasy of all time like a jealous and unmerciful king.
Reading this story has left me in awe and not a tiny amount of disbelief regarding vending machines in Japan. I can't tell what might be just made up for this story, and what is real anymore. If true, Japan's vending machines are a culture of their own, an alien existence somehow transplanted into the technoscape of Earth by some kind of mischievous alien box deity.
The writing is competent, the characters are there, there is plenty of humour and the elevator pitch twist reincarnation is present every step of the way. Our MC faces adversity, adventure, fun times and dangerous times, all with some kind of actual pacing going on. I wouldn't be surprised if the author was an LN veteran doing a fun little parody side-project for a while. The vending machine can't even offer potions! That is just unimaginable!
Only a few places feel a bit boring, but the story moves on and changes all the time. No grinding, no repetition, no quests and very few stats, all competently written for an LN and readable. If you're looking for a light palate cleanser to remind you that isekai still has hope, check it out.
This is the story of the most OP vending machine in the history of vending machines. And that's a promise.