Here are some thoughts - take them with a grain of salt.
- The audio is a bit monotonous, maybe if the tones shift up in pitch as you add more and more letters to your word.
- I got an orange letter and used it, but wasn't sure what that gave me. With the timer, you don't really have time to stop and look to see how the score changes - so maybe some sort of visual feedback there.
- The game over sound is terrible - sorry for the bluntness, just my .02
- I thought it was fun - I found myself wanting to quit to go do something else (I have a short attention span sometimes), but I'd level up and want to keep going - so I think there is something there.