I finished the early access beta version of the game, was a lot of fun. I'm playing through again now it's full 1.0 release and I'm enjoying it again. The extra polish and quality of life stuff they added is really nice. And the gameplay and combat is smooth.
But what I would say is that there is still too much potential to get roadblocked by certain bosses that hold key ability or technology unlocks. Certain bosses can be difficult if you don't have the right build or skills. And if that happens, there's not really any alternative route to progress.
This is less of a problem co-op, depending on what other players are around, but can be a problem solo where you can reach an impasse where you can't improve your character enough to progress. Essentially it's a skill issue, but some boss fights do have some particular quirks that make them harder than their level would suggest.
Obviously if you're solo on a private server you can tweak the boss difficulty down to trivial. But that just feels cheap and loses any sense of accomplishment (I already feel bad because I turned down the decay rates).
I'd really hoped they might rethink how the unlocks work, or at least provide some alternative routes. But essentially it's a game about defeating a long series of bosses, so it's baked into the design.
Anyway, overall it's a very enjoyable game.