A good tripod can do more for your photography than anything else. It will eliminate camera shake, and by forcing you to slow down, it can make you think harder about your pictures and take more care over them. On the other hand, tripods are heavy, bulky, and generally a nuisance.
Good ones can be expensive, too.
More than almost any other photo accessory, too, tripods are a compromise. The dream would be an ultralight tripod that collapsed to almost nothing, extended to a mighty height, was as solid as the Rock of Ages, could be set up and taken down in seconds, would last forever, and cost a pittance. What you have to do, therefore, is choose your compromise carefully, and it makes sense to look at each feature in turn. Other things being equal, a heavy tripod will be more stable than a light one. But other things aren't equal, and a great deal depends on design and materials.