I'd say pretty much, yes.
For CBB4 the final week poll predicted Chantelle would win by a landslide. It didn't predict that Michael Barrymore would be second though - the fact that people often vote for more than one housemate in the final is a variable that the polls on this site don't really take into account.
For the BB6 final the poll correctly predicted throughout the week that it was nip-and-tuck between Anthony and Eugene. After Eugene won half the money in the penultimate night twist there was a run-off poll and Anthony was the clear leader there.
The eviction polls have been generally accurate throughout this series also. For example Imogen's eviction percentage was 62% and the poll here predicted 63.1. Mikey's eviction percentage was bang-on level with the poll here - 48.5%.
Of course (as politicians are fond of saying) the only poll that really counts is the one, the result of which, will be announced at the end.
