I'm not clever enough to come up with a description for COQ10... But, its a very under-appreciated supplement! Most research suggests that COQ10's biggest benefits relate to heart health. Check out this description from the highly-credible Mayo Clinic:
 
Coenzyme Q10 (CoQ10) is an antioxidant that your body produces naturally. Your cells use CoQ10 for growth and maintenance. Levels of CoQ10 in your body decrease as you age. CoQ10 levels have also been found to be lower in people with certain conditions, such as heart disease, and in those who take cholesterol-lowering drugs called statins.
 
CoQ10 is found in meat, fish and nuts. The amount of CoQ10 found in these dietary sources, however, isn't enough to significantly increase CoQ10 levels in your body.
CoQ10 dietary supplements are available as capsules, chewable tablets, liquid syrups, wafers and by IV. CoQ10 might help prevent or treat certain heart conditions, as well as migraine headaches.
 
Evidence
Research on CoQ10 use for specific conditions and activities shows:
Heart conditions - CoQ10 has been shown to improve symptoms of congestive heart failure. Although findings are mixed, CoQ10 might help reduce blood pressure.
Diabetes - Some research suggests that CoQ10 may help reduce low-density lipoprotein (LDL) cholesterol and total cholesterol levels in people with diabetes, lowering their risk of heart disease.
Statin-induced myopathy - Some research suggests that CoQ10 might help ease the muscle weakness and pain sometimes associated with taking statins.
Migraines - Some research suggests that CoQ10 might decrease the frequency of these headaches.
Physical performance - Because CoQ10 is involved in energy production, it's believed that this supplement might improve your physical performance.