I have to say, it's not very engaging.
The enemies do not have interesting behavior. They do not challenge any of your abilities as a gamer: in the end it felt like it was just a battle of numbers against numbers (which one of us has the best stats). Sure you have to jump and attack at the right time, but it gets old REALLY quick. The strange hitboxes of the monsters do not help either.
And what's with the insanely large amount of health they have ? It's not entertaining doing the same trick over and over, for minutes long, trying to get only one monster down to zero health.
Also, and that might be my main complain right now: the synergy between the ennemies is not good at all. They do not complement each other, and their repetitve behavior makes them swarm at you in one big mess, throwing all their projectiles at you, most of the times leaving you no other option than to flee, and leave the room from the door you got in. I'm not talking about rooms way above your level, I'm talking about rooms you should be able to clear because you have the gear to.
Now, these complaints might seem useless if it was fun or interesting to move your character around the world. But I tried almost every class and none of them felt right. Trying to unlock the abilities is hard, but once you get some, you breathe again: at last, something new ! But in the end, it all falls flat. The double jump alone prevents you from accessing certain platforms, and i wondered why is wasn't unlocked from the get-go. Same for the dash ability. And none of them was fun to use.
I get it: maybe you want us to spend lots of time in the game, wandering the corridors, finding our way through the folders. It's part of the experience (i guess?). But if there is nothing rewarding in the end, it's not worth it. Because right now, the combat is not rewarding, to me at least: it's boring. And the whole game feels the same way.
And it hurts to say because i want to like this game ! I'm a fan of platformers and an RPG enthusiast... but right now, I have to say i'm not enjoying my time with AdventurOS.