I have it bad. Itches like a bastard. T-gel clears it up, no other anti-dandruff products do anything. Quite expensive though, 8 quid or something for a bottle. Also having really short hair helps. Apparently had it since birth so probably gonna have to keep forking out.
BONUS FACT - when I was born I had a full head of hair and a hairy back - but my back has no dandruff (or hair anymore)