It's a nice concept and got it working perfectly with Ducktales Remastered but it has a steep learning curve if you want to try and create your own mappings and customizations. I have yet to successfully create one for a few games where there are no templates.
Not sure if it ever will be possible but if you care about achievements you can't unlock them while using GestureWorks. Because it hooks into Steam, Steam believes you're playing GestureWorks and not the game itself so achievements don't unlock. I hope they can figure out a way to unlock them during play but wanted to put this in the review because if you don't read the fine print you may miss that detail.
I wish Steam offered an option beyond yes/no recommendations. Kind of like a Not Yet or maybe. I cannot recommend this app if you are not technically inclined or if you care about Steam achievements or rarely game on touch devices.
If your touch device is where you game the most, then yes, worth the $10 right now.
Overall though I'm going to choose No in my recommendation because I believe more and more developers are going to be implementing touch controls into their games. Civilization V, Trine 2, PinballFX, Total War Rome II, Octodad, Broken Age all have native touch controls and a lot of others work fine even without native controls like The Witcher.