I came late to BB1 but got hooked on it immediately. I was looking forward to BB2 immensely and, once again, got hooked on it straight away. After waiting impatiently for BB3 to start, I was hugely disappointed with it and, if it hadn't been for Alex's humour I would have stopped watching it after week 3.
Like ROB, however, I'm now looking forward to BB4 and I agree with everything she says. It couldn't possibly be worse than BB3 and it might even be as good as BB1.
As for BB2, this remains unique and enormously special and, IMHO, will never be bettered.