First of all: until you finish the game, you wouldn't know it has no ending and it actually is NOT finished by developers.
I won't say "don't buy", since, at least at first, the game is super cool, and it might give you a couple of really pleasant hours. Or maybe even tens of hours - if you like the grind. But by all means, DO NOT expect any ending. You can 100% it if you'd like, it's not so hard and not so time consuming, and the achievements are pretty. But don't do it for the sake of the story. The story is unfinished by the devs, the very end is simply missing.
Now, my humble opinion on the gameplay:
It's an ingenious mix of roulette and grind. It feels like nicely balanced and cute grinder at first, but in the end it would remove last bit of oxygen from the room. It will reward you with generous, cheat-like skill bonuses in the end game, but the trick is: it barely helps to "fix" the hell of requirements that the game will set before you. Mostly it's that you need some rare item, and till the endgame it's really hard to obtain one (but you've already got dozen, because *grind*, so they occasionally dropped to you once in a while). But the game doesn't care that you already has some, you need to obtain one. Or you've already spent 10 you had and you need 2 more. Anyway, in the endgame, you still won't be able to just farm such things. It's just that now you have a somewhat-cheaty random drop on every action, so that previous rareness of items is now replaced by "fun roulette grind". It sounds fun, but after ~50 hours of monotone grind such twist actually feels gameplay-breaking. Imagine DOOM, you're getting good, you try and repeat, and finally get to the final level... which is a huge damn arena with millions of monsters, but you're immortal, and there's only Wabbajack in your arsenal. It's perfectly beatable, it's kind of fun, but it could take a lot of time to beat and it's highly unsatisfactory after all the road behind.
What's even worse, there's no final... something. It's no surprise there's no battle - there's no fighting mechanic in the game, and from the start it tells you that you've fought enough. so it would be naive to expect the final fight (or it being an actual *fight*). But there's also no final dialogue, no cutscene and no NPCs. There's no acknowledgement whatsoever of the hero being finally able to jump to the World below. Guys tell you that they would help you there, down below, and yet there's no contextual dialogs with them when you get to that pit. Just nothing. I mean, devs could've finished this with just a one-liner. Just as a fact of acknowledgement that the player got there. That the player got there... I tried so hard, and got so far, but in the end, noone cares. Not a single NPC acknowledge my ability to go down the pit. Just a dead end with a coule of developer-tester-grade cheat items. I don't want them. I want my wife to acknowledge what I've reached. I want Dark to say at least "wow, you've got there". I want Dalton to joke about the pit. I mean, I want some closure. The game hurt me deeply. Don't you ever leave an ending in your game like this. Ever.