Like Tire-Burner said, it's difficult to get the hang of, but fun once you do. I like the mechanics for throwing the dart. It's simple, but surprisingly versatile. It was entertaining trying to match getting the correct strength for the dart throw with the rotation of the target to get a good score and, especially, avoid hitting one of the skulls. Overall, I had a lot of fun with the game once I got into the swing of things!
After a little while of playing, though, it got a little repetitive and I wasn't entirely sure what I was aiming for. I think that's somewhat unavoidable, given the nature of the game, but it might have been nice to have something more to mark progression to higher levels than just a progression bar and a number. The congratulatory pop-up when you level up was nice. Also, the shop confused me at first; there's not much indication of how much currency you earn or why, and it took me a while to realize that each play cost five darts, which needed to be bought or renewed through the shop.
(Edit: I played a little more after writing this review, and got another level up pop-up that did give me extra darts and currency; I'm not sure if I simply needed to get to a particular level for that to happen, or if I'd been clicking through previous pop-ups too quickly. If so, part of my review may be entirely inaccurate, haha, but hopefully it's still something to keep in mind.)
Still, the game is very fun! I think it's a good game, it achieves what it meant to, and the simplicity is overall charming. A little more explanation might have been nice, but it's all pretty self-explanatory and not too difficult to figure out independently.