[Product Question] I want to start using a Vitamin C serum, can anyone tell me if this is worth my time and money?

Beauty Tips For Body Care
http://www.amazon.com/20-Vitamin-Ferulic-Acid-Serum/dp/B0036BI56GIf it's not great, what are some comparable (price-wise) suggestions? How do you know if a product you are looking at is worth it?Thanks!
Girls Blog 2015
Submitted by Aphrilis