There's been a lot of noise around Kybella/ ATX-101 but does anyone know if it actually works?

Yes...Kybella works!   It is made of deoxycholic acid,  and works by dissolving fat cells.  You will immediately see the effects of this fat dissolving action, as your under chin area will begin to feel very "jiggly" and you will have some slight swelling as this chemical reaction takes place.  As for downtime, there really isn't much.  You will typically have swelling in the area for a few days, and it is possible to have slight bruising.  The full effect of the treatment isn't typically evident for about 8-10 weeks, and treatments should be scheduled about 8-10 weeks apart.  
To be sure, see two or more experienced, licensed and board-certified providers in your area for a complete evaluation to make sure you are a good candidate and that it is safe for you to have treatment. I hope this helps.

Kybella was extensively studied prior to its FDA approval.  Because Kybella is a medication vs. a laser procedure, its efficacy has to be demonstrated in many patients and the degree of improvement has to be far greater than laser procedures in order to receive FDA approval.Kybella wouldn't have received FDA approval for moderate to severe submittal fullness if it didn't work.  In my experience both in its use and as a clinical trainer in its proper use by other physicians treatments have failed to match those results seen in the patients submitted for FDA approval due to improper technique.  In addition, 2 to 4 treatments are required.  One treatment will not give you optimal results.