Has anyone tried ultrasonic liposuction procedures? What are the results?

Can be good. Ultrasonic liposuction is a tool that allows the surgeon to use energy to break up the fat and create heat for some modest skin tightening. Its particularly good for areas with very dense, fibrous fat, like male breast tissue.
Can be very good. Ultrasonic liposuction uses ultrasound energy, just one of many different energy modalities delivered to the fatty tissues before or during fat removal via a thin tube (cannula), aka liposuction. Proponents of ultrasonic energy claim a more selective and gentle removal with potentially less bruising and swelling.
Yes. Same. There are many different liposuction technologies available; each claims to be better than the other. Each is also heavily marketed. In my opinion, much more important than the specific technology used (when it comes to the surgical outcome or “effectiveness” of the procedure) is the surgeon using the “tool”. Patients are responsible to do their due diligence and select surgeon carefully.
Depends on Surgeon. There are many different options for treating the area under the chin and neck. Liposuction is one option that can provide excellent results in the right patient and with the right surgeon. There are many doctors who are not trained in plastic surgery or dermatology who have "gotten into the liposuction business". Make sure your surgeon has taken more than a weekend course.