Well..
Ok.. I am rating this low. Not because I absolutely hate the concept. It could be fun.. But your execution leaves a bit to be desired. Some things that struck me while playing:
1. The controls are a bit awkward, and take a bit to get used to. This is a really easy fix. Try putting a highlight around all of the gears that are going to move (you can use 2 colors, one for the selected gear one for those that will move). Also because of the nature of the game it would make more sense to have it mouse controlled, or at the least give the option of mouse control.
2. Design. Although I am sure you like the font that you used, it is difficult to read with the colors and the background. This is also an easy fix. It is a word game, try using bold easy to read fonts (like Arial), be minimalistic with your background and colors. At least on the playing field.
3. You need to add more explanation. You should explain the Add and Drop buttons. I noticed that I kept getting more time, I have no idea why, but when I ended the game I had almost 4 minutes and we are supposed to start with 2. So what is the deal with that.
4. You may also want to limit the number of adds and drops. Or make them earned by forming words of a certain length. Try playing around with it a bit. Having as many as you want makes the game practically un-loseable.
Due to the flaws in the game I found myself simply adding till the field was full, randomly turning blocks of gears until I figured I had pretty much cleared what I could, dropping what was left, and then adding again. And amazingly without paying any attention at all to the words my score kept going up and my time kept going up. I didn't find any sort of challenge or strategy to the game, and it seemed like words had very little to do with it.
I am giving this a 2/5 which is passable, because I think the idea has promise and I think you should take some time listen to what people have to say about it and work on it some more.
I am giving this a 2/10 because as it stands it isn't very fun, and I think it ends up falling out of being a puzzle game and being more of a key mashing game with very little rhyme or reason.
Keep trying.