4 stars with cost as a factor, 5 stars without.This product is not for everyone.If your car is just transportation and gets a quickie car wash a couple of times a year, don't bother.If you like a clean car, but think the clay barring is too much extra work, think again. This may be for you after all.If you're obsessive over making your pride-and-joy look its best, this is definitely for you.The first time someone introduced me to clay bar cleaning, they made it sound like you had to press the clay onto the surface, a few square inches at a time, and lift out the contaminants like you were waxing your legs. Not so. It's just one fairly easy extra step to a basic cleaning.Give the car a light wash to get any large, abrasive particles off the surface, then spray with the Speed Shine and wipe the clay bar over it, just as you would a cleaning cloth. Depending on the condition of your finish, you will feel a tiny bit of resistance as the clay slides over the slippery surface picking up the particulates that normal washing doesn't get. Then spray and wipe with a microfiber cloth. Additionally, if you're getting ready for a car show, or just want to look great, follow this fairly easy cleaning with a polish.I've used other products a few times with good results. It's hard to say one is clearly better than the other, but Griot's certainly seems to be at the top of the pack. The amount of fluid provided is much more than the off-the-shelf competition, and while the amount of clay provided may seem small the first time you buy it, it's actually more than the other brands I've used as well. Griot's only costs a couple of bucks more (for more product) and produces great results.I used this on a dark metallic blue Mustang (Kona blue) - a finish that's enormously difficult to keep shiny and accumulates countless micro scratches. Results were a shiny, deeply reflective gloss, and even though I do not believe clay bars claim to fix micro-abrasions, they definitely appeared reduced. I lightly rubbed my fingers over the surface afterwards - silky smooth.