I used the Netbeans builder back in college, and it was adequate for quick mockups. However, it usually ended up being easier to do the final version by hand, as the Netbeans layout (Absolute; at the time (?) it wasn't part of the Swing toolkit) typically didn't handle resizing well at all. I don't know if it has changed/improved since.
Since then, I've done it all by hand. You get much more control, and once you understand the layouts and containers it's a fairly quick process.