Forget the depths, there's so much to see in the shallows
Dave the Diver is like like a teppanyaki chain restaurant: it can appear hackneyed and silly, and it's not the best-tasting meal you'll ever have, but the energetic showmanship and variety of food sure keep it interesting.
Dave gets a lot of nautical mileage out of introducing new features, environments, and even gameplay at a pretty high frequency. I don't just mean its WarioWare-like microgames for harpooning fish and preparing dishes, either -- there are entire upgrade trees, resource management systems, stealth-action interludes, and other novel mechanics suddenly appearing every couple hours.
Most of these ideas would be pretty mediocre on their own - whether because the UI for managing fish hatcheries isn't very intuitive, or because a bullet-hell boss fight is kinda frustrating - but they never outstay their welcome, because Dave the Diver's always got something new just around the corner. (Plus, boss battle checkpoints are mercifully generous.)
And it continuously delivers those ideas with such enthusiasm, with such consistently fun charm, that it's hard not to crack a smile at this goofy fuckin' game.
That promise of delightful novelty is what kept me going for one more round one more dive, despite various rough edges in one system or another, through Dave the Diver's impressively lengthy story -- easily 20 or 30 hours of fishing and sushi-preparing and mystery-solving and world-saving. I can't stress this enough: mermaids are one of the less surprising parts of Dave's story.
Unfortunately, once the main narrative is over, it's hard to stay motivated for any secondary objectives Dave might have left. Collecting more MarinCa and sourcing more picky customers' ingredients does start to feel samey after the story-driven gimmicks have dried up.
Up 'til then, though, Dave does a commendable job of keeping it fresh.
Better than: Animal Crossing: Wild World
Not as good as: Battle Chef Brigade
Alternate summary: "Like Grand Theft Auto with its irreverence and disparate minigames, but instead of stealing cars, you catch fish."