It seems pretty fun. Playing on an android tablet with touch controls, it was kind of hard to see what special characters did. If I touched them in a word it would just deselect them. If I tried to hold it the explainer tip would come up, but it wobbled around a lot and lowered the opacity to the point it was basically unreadable despite all the other game text being clear.
Otherwise it seemed good. In the speed mode, the letters fell pretty quickly, but I've never been great at these kinds of games. It might be nice if the overflow timer didn't start until the letters had settled, as it's difficult to start spelling when the letters are still merging and moving around.