I'm enjoying it and I do have genuine fun doing shared dives, finding new creatures, going to the bottom of the ocean and discovering mysteries on the board but the story mode is a whole lotta nothin and being able to find all the creatures at random really detracts from the wonder I felt playing the first game. The larger and rarer (and in Thanatos' case, scarier) creatures don't excite me that much because they're everywhere, so nothing feels novel. That being said, customisation is fun and it is a nice, relaxing game if you view it objectively. Still, being in a series does inevitably warrant comparisons to previous games so I can't say it's not disappointing in some aspects.
In short, it's undeniably fun but don't go in expecting anything like the previous entries.