I have never in my life felt strongly enough about any product to write a review, but here goes.
I am a naturally cynical bloke that had dandruff for 30 years. (Not a snowstorm, but noticeable if I wore a dark jumper). I'd tried most of the well known products to relieve the flakes and the itching. None worked!
For no other reason than it was all the local shop had one day, I bought L'Oreal's anti-dandruff shampoo which claimed that it would be effective after one use (it was) and I was stunned by the results, and have never looked back.
To be clear - I wash my hair only when it needs it, and certainly not every day! I have no dandruff anymore AT ALL, and best of all, no itching (which used to drive me mad). I have no thoughts whatsover about it's fragrance or whether it gives me a glossy coat - I don't care!
If you have an itchy flaky scalp it's definitely worth a try. Perhaps it's my skin type or whatever, who knows? It works for me.