This manga is OK, but it lacks a defining gimmick. I give it a very standard 7/10.
Like, normally you have a 'but' in the manga description, right?
"The MC is reincarnated in their favourite action-RPG gameworld... but it's as the villain."
"The MC is reincarnated in their favourite action-RPG gameworld... but he's stuck with a joke Class."
"The MC is reincarnated in their favourite action-RPG gameworld... but he needs to defeat the demonlord in less than a week."
"The MC is reincarnated in their favourite action-RPG gameworld... but his use of exploits crashes the economy and he becomes a fugitive from the law."
Anyway, this MC is reincarnated in their favourite action-RPG gameworld.
And... he goes around playing the game as intended.
The most noteworthy thing is he's bringing an alchemist girl with him and power-leveling her, and that nobody else treats this as a gameworld with known and catalogued exploits, like the MC does.
And also... The manga makes a big deal about how there are 1000+ Classes to choose from, but then the MC just picked the absolute bog standard Class "Hero". And it's not like Alchemist is a rare occupation in mangas either.
Way to ignore the most interesting part of your setting, dude.
Overall, it's not bad, It just seems... humdrum.