One of the best puzzle games that you probably haven't heard of. I'm glad I stumbled upon it! It has a nice minimalistic, aesthetically pleasing visual style as well as simple, rather intuitive gameplay mechanics. To me it's more addictive(I don't usually use that word referring to a game) than frustrating.
I do have just a little bit of constructive criticism, though. It would be good to have an instruction page, it's not too hard to figure out the basic moves etc. However, it is a little unclear what causes a game to end. I guess it must be that it ends when one doesn't clear enough of the symbols in few enough moves and the board gets too "backed up", but you can't really see where you stand. I think it should be clearly visible on the screen. The way this is right now, there are too many "why did the game end?" moments. This is a good game that could be really good with just a couple of changes. I attempted to tell this to the devs, but their website is almost all in some kind of Chinese(I think). Bottom line, I say try this free version if you like puzzle games and want something a little different than another match 3.