If your forms are simple and not dynamic then a GUI builder is perfect. The more complex the form the less benefits you will get from using GUI builder.
The company I work for does just that. Simpler apps are developed with the GUI builder and more complex apps are done by hand. Once there are enough hours trying to work around the GUI builder's limitations it is usually abandoned. Also each GUI builder is not created equally so it will take some evaluating on your part to determine under which situations a GUI builder is appropriate. (The NetBeans GUI Builder is pretty good.)
Personally I like to use GUI builders to come up with the overall layout of and app/form and play with the different layouts but then I convert that to more readable code and do the rest by hand.
