cabin crew were told to sit down and strap in. I haven't heard that order being given much ... does that mean it's pretty bad?
Often if we get plenty of warning that turbulence may be significant enough to pose a risk to unrestrained cabin crew we'll tell them to be seated via an "interphone" (telephone) call. The passengers will probably already be strapped in and blissfully unaware of the extra precautions. We generally only make a announcement over the public address if we need them seated quickly, and that generally happens if we get little warning of the turbulence, it doesn't neccessarily mean the bumps are going to be especially bad.