Wow! This is a very straight-forward question, yet difficult to answer simply. I suppose that the best answer is this: There will be no major changes to your images using a fixed, or prime lens. But, there are improvements to the technical attributes of the image that you might notice. Things like sharpness, contrast, corner sharpness, etc. But the actual image is not improved.
The image is made by a photographer that has an eye for art, composition, and interesting subject matter. There are people that use disposable cameras to make wonderful images that hang in galleries! The lens is one of the lesser parts of the construction of a great photograph. The photographer is the most important part. If you started playing the piano, a Steinway piano isn't going to make you a better pianist, but it can produce richer sound.
That being said, I like the quality and sharpness of the Limited series. Crisp, sharp detail is something that I am interested in. But, there is nothing wrong with the kit lens. It makes some excellent images. Go to the Pentax Photo Gallery to see some of the wonderful pictures taken with the kit lens:
PENTAX Photo Gallery