is the gameplay good or is it grindy?
It's very grindy, in an unusual way.
There are dozens of collection points per map, which respawn every day, so you'll spend a huge chunk of time just going around collecting items.
Random encounters aren't that bad, though very heavy on the 'random' aspect (highly variable occurence, 3 steps is just as likely as 300), and can be somewhat controlled by choosing at pillars scattered around how high a spawn rate you want.
What *is* bad, are the monster nests. When fishing or collecting from large collection points (the objects that don't disappear after collection, like box piles), there's a chance you'll fish up or trigger a monster nest, which are swarms (5+) of enemies and significantly tougher than the random encounters from walking around. They can make your game a living hell, especially in certain areas where their trigger rate is stupid high (tropical beach for example).