Low cost. Easy to install and highly decorative. There is a vast choice of colours and sizes. Easy to move around if some work underground is required. It can be treated with a weed-killer. If used in a path, kerbing will help to keep the gravel in place and off the garden. If the gravel is too close to your front door, it will end up in your house (hence the need of top-up), also children seem to be very fond of filling gullies with the gravel! Well suited for protecting plants from weeds. Downsides: it requires maintenance, holds dirt and is difficult to clean.