Im amazed and pleased GoG has this much cheaper then steam and it looks interesting, but Im curious if this is worth buying now or waiting for a sale. I've heard some people saying it feels more like a 9.99$ game

I would say it depends on what you expect from a game worth of $18. I think this review sums it up nicely.

Definitely worth a buy I think. Hard to compare it too another game very fun to play, and even just to watch someone else play.