I LOVE this product! I bought it as a spur of the moment thing and have never regretted it for a second. I only have to use a tiny bit under each eye so it's lasting for ages. It helps to disguise the dark circles with a lovely brightness and is a great base for concealer/foundation.
I can even get away with wearing just this under my eyes, instead of my usual 3-4 layers of creams, concealer and foundation!
No idea about the long term effects - whether it really reduces the dark circles etc. But it does enough for me that I will definitely continue to use it.
I highly recommend this product.