We've all seen the TV commercials showing a happy customer having a rock chip or crack in their windshield repaired. On TV, the chip or crack is not only repaired, but it magically disappears. It makes for good TV, but disappearing rock chips are an illusion.
When you have a rock chip repaired, the process seals the chip, cleans up the break and gives a good measure of protection against further breakage. What it doesn't do is make all evidence of the chip disappear. Rather it does make it more visually appealing and clean, but you will still notice a small blemish on your windshield.
Another question that is often misrepresented on TV is the size of chip that can be effectively repaired. The general wisdom is that any chip greater than a dime is NOT a candidate for repair. With the windshield being such an important part of the structural integrity of modern cars, any chip larger than a dime significantly degrades that strength and that windshield should be replaced.
Rock chip repairs are a very effective and reasonably priced option for repairing your windshield. However, they do have limitations and keeping your expectations in line with the realities of the process rather than the TV illusion will let you make a better decision on whether to repair or replace.