Gel paint stripper is best used on specific surfaces. Its application, use and price is different from other forms of paint removal.
Gel paint stripper is a very thick substance and is either clear or white. Because of its texture it clings to a surface better than a liquid stripper. It is easier to use and less labor intensive than sanding a surface that you need to strip of paint or varnish.
If you are wanting to strip a vertical surface that can't be removed to the outside or to lay horizontally, then gel stripper may be the best choice for you. This type of stripper clings to a vertical surface and doesn't run as easily as a liquid. You can keep it in one place for a longer period of time allowing it to penetrate and do its job.
Gel is also good if you are working with carved or embossed wood. The stripper soaks into small areas and crevices to remove all the paint relatively easily. For instance a carved fireplace mantel or doors with a lot of trim would be the perfect usage of this product.
Another good use for this product is on pieces you are stripping that has a very heavy buildup of paint. The gel will stay wet longer than liquid stripper and this allows it to soak through multiple layers of paint. You can test the area to see if you see wood yet and if not, just put on another bit of the stripper on top of the old.