There is a 'lite' version now for free. I tried it and it played fine and everything, but it felt similar to Fire Words, which I already have and like, so I am not sure I would pay for it. The difference is that when you use a letter, that space turns lighter, and you can't clear the board until all the spaces turn light. It was a fine game, just a little late to the party, and for me, I have other ones I enjoy. I am not seeing what this one really adds to the mix.
The lite version was offline for a short while, but now seems to be available again. Latest version seems to have added ability to drop gems onto the letters for better scoring, and a new ranking system. I'm still trying to get to "Arcane Grandmaster" rank it's kind of a surrogate for Bookworm