Noiseware occasionally improves your photos (photo samples)
While it doesn't provide a dramatic improvement if you only view photos on your phone, there are cases where it might be worth the three bucks.
You can tell the difference
If you look at a really noisy shot like this crop, at 100 percent, on your computer, you can see that Noiseware does a pretty good job cleaning up the artifacts, even simply using the default settings. The out-of-focus areas do lose some detail becase of excessive smoothing, but there's only so much that can be done with image noise. This isn't TV.
The original photo was dark, and bringing up the exposure added the noise shown in the previous image. However, while the exposure-adjusted version looks significantly different, you don't really see the affect of the noise reduction unless you're viewing it at full size. (Note that I couldn't exactly preserve the exposure.)