Would you recommend fillers to fix a 24 year old's festoons? (photos)

Juvederm can work reasonably well in this area and may last 6-9 months.   You may consider several treatments with juvederm, but may want to consider fat grafting to that area for a longer term solution.   Fat grafting can fill the concavity, will last much longer and should remain for many years.  

Despite your young age, you have depressed areas in your cheeks which are of aesthetic concern.  These areas are largely due to changes in your underlying facial soft tissue anatomy.  They can be difficult to correct.  I do find that injectable fillers such as Perlane or Voluma can be of benefit.  As this is a more complex condition and then some I would make certain that your injector is extremely experienced and his treated patients with this condition previously.  Best of luck.

You have a prominent malar fat pad.  These can be tough to eliminate.  If you put some filler in just below it where it is hollow you may be able to smooth out the transition so you don't notice the malar fat pad.  Sometimes some laser on top of the fat pad may help to tighten the skin and flatten it a bit, but results are variable. 

The photos suggest volume deficiency rather than festoons. There is a prominent trans cheek furrow which delineates different fat pads in the cheek. You would likely do well by starting with one vial (1 ml) of a medium type hyaluronic acid gel such as Restylane with lignocaine, delivered via a single entry point and canula on each side. Then see how it is about a week or ten days later and decide if you require a second vial.

Festoons can be tricky to treat appropriately - fillers alone typically don't work well.  A combination treatment is the best option - this includes reduction of the fluid that is built up in the area (avoiding salt, too much alcohol, smoking, etc), gently smoothing out the irregular areas that remain with either fat or filler in the high cheek area (Sculptra works great for the cheeks), and a topical skin treatment (lasers or chemical peels).

It does look like you have a minimal fullness that could be categorized as a festoon.  This is an annoying area of excess skin, a little bit of fat, and some people have recurring swelling.  It is separate from the lower lid and can be a real challenge to correct.  I'd be willing to bet that someone in your family has these -- you can get an idea of what this is going to look like many years from now.   For the minimal defect you have, it would be worth trying a little bit of filler to see if it would plump out that line.  It might not, because there are tiny 'adhesions' that are holding that skin down right there, but you might be successful and that would be worth it to you.  Some people put steroids in the lid/cheek area above the little crease, but that's a bit extensive for what you've got going on and is usually reserved for people with chronic edema.  I'd recommend Restylane or Belotero - both are hyaluronic acid fillers that can be injected in small amounts - you'd probably need only a half a syringe.  Juvederm is also a hylaluronic acid filler BUT is just a little structurally different from the others and has a tendency to cause prolonged swelling in the eye area - exactly what you would not want (it is okay in other parts of the face).  The other fillers are not recommended close to the eye - can create lumpiness.  Also, the good news about hyaluronic acid is that it can be 'erased' with an enzyme (injection) if you don't absolutely love it.   Look for a board certified plastic surgeon in your neighborhood - they will be quite familiar with fillers.  Good luck!

You do not have classic "festoons." However, you do have under filled cheeks which are seen best in the 3rd picture, the oblique one. A filler would markedly improve the problem. There are 2 options. First is an off the shelf filler such as Juvederm Voluma or Radiesse. Presently, I  prefer the former as it lasts longer and gives more lift, though it is more expensive. For someone your age, the best option would be using your own fat. This may take 2 sessions about 4 or more months apart to achieve optimum contour. See an expert injector.