As a fan of Monster Trainer games since the 90s, this is SOO much more than a ripoff, or cheap cash-in. Nor is it in danger of being sued by Nintendo. Does no one remember any other monster training games other than Pokemon?
Dragon Quest 5
Monster Rancher
Digimon
Yokai Watch
KH: Dream Drop Distance
Monster Hunter Stories 2
Pocket Mortys
TemTem
And now, Palworld

I already think my money was well spent. I've had tons of fun already, and see so much more on the horizon, as I'm less than 20% into the game's current content. I've had several memorable interactions with my Pals, and some even feel more meaningful than any I've had in any Pokemon game. in fact, Pokemon has shied away from the very aspects I enjoyed most about the setting, whereas Palworld embraced them. Here's a few things Palworld does BETTER:
Petting Pals is better than PokeMonAmie
Cooking with pals, and feedbags/bowls are better than Pokeblocks/Macarons
Over-leveled Pals are better than over-leveled Pokemon
You can run around the world with a Pal by your side (not in Pokemon since gen 1)
You can mount, hang from, or carry many different Pals
Palworld doesn't FORCE you to play lawfully in the setting
You can catch non-Pals
Pals are actually used for their innate powers in society and by the player (only in Pokemon's show, never in game)
There's a reason to catch more than one or two of each Pal
Much larger Map
More stable than modern/comparable Pokemon entries
(Plus a lot more, but I gotta draw the line somewhere)

Lastly, as of this review, there is no substantive evidence that the Dev used AI art for this game (there is for their previous game), and has gone on record stating they actually had to learn modelling and animation, because there wasn't an acceptable shortcut for making compelling Pals. This is also not a blatant "asset flip" as if there are base unreal assets in game, I honestly haven't noticed which ones they are. I suspect some of the tools and item icons may be, but I've not seen them before, and I think most fit the idea they're conveying. I also assume any bought assets won't remain after full release. The Pals occasionally have similar design elements to existing designs by other IPs, however, those "originals" weren't very original to begin with. most of those are just earth animals with a magic element applied, or are a folklore creature from human history. Not even one pal has truly felt to me like any other thing than itself. for example, Mareep was based on a sheep, and Lamball is also based on a sheep. But I've never once conflated the two, as they are MORE different from each other than what they are based on. Lamball is also cuter in my opinion. And it can operate a gun.