They look great, are vurrrrry smoooth (if set up properly,) and have a great warranty. But a lot of other headsets offer that nowadays as well.

For example, these, which I just stumbled across today: http://www.benscycle.net/index.php?m...9379d4ed2d03dc. They're German, and apparently quite well-made. Cane Creek models can be really nice, too. 8-year warranties on most of theirs, I think. I'd be lying if I said I'll never buy another King headset, but there's other good options. If you're planning on building a really decent bike, though, I'd say $80 would be a good starting point for headsets.