It's a wonderful primer if used correctly!
Cleanse, tone, moisturise. Apply a thin layer of Beauty Flash Balm and whilst still moist, apply foundation and concealer. It's magical in that in makes your foundation appear flawless, skin dewy and has a brightening effect.
Most people run into problems when they don't apply their foundation whilst the BFB is still moist - that's key. If you apply too much, you will get a crusty/ skin peeling effect.
Go to the Clarins counter and get them to apply it followed by foundation/ light make up. Take a pot so you can do it yourself before making an investment.