Fireworks isn't going to become more popular than Photoshop any time soon but that doesn't keep it from being more powerful for certain tasks. It's a favorite tool among many designers. This article is a great primer because it runs through how to do many of the common things that UI and icon designers would use it for. You can see how easy it is to do paths, gradients, control stroke, etc. If you've been wanting to try a different image editing app check out this post.