Minecraft Dungeons is a great dungeon crawler game, that still has room to grow. The story is only about 2 hours long, not long enough.
The loot system is great, aside from not being able to trade with other players.
The unique bosses, mini bosses and difficulties are well done.
The reason this isn't a 5 star is because the game is incredibly repetitive after the Default mode, the loot rarities are limited to 3(common, rare, unique) and there is a lack of content outside of the story missions.
Aside from that, Minecraft Dungeons in my opinion is worth playing, even though its not perfect, it still has much room to grow.
It took Minecraft years to get to where it is today, so I believe we should be patient with Mojang as they better the game.