While not the worst, the graphics do not really stand out as polished and look somewhat dated. While it does fit within theme of being a grimy universe with many foul creatures, it does not compare to many AAA dungeon crawlers out there such as Diablo III.
Just install steam and download the game. No purchase required and the only thing locked behind paywalls is cosmetic accessories and inventory slots of which you can waste money on cosmetics, but you won't fall behind if you don't want to spend money.
The developers have a strict "no pay to win" mindset on this game. Which is GREAT since everyone has a fair chance at winning. The only in-game purchases are decorative, extra stash slots, non combat pets and better graphics for your weapons.