IMO, the biggest surprise would be Jacques Villeneuve winning a race. The biggest disappointment would be Renault (or any team) completely dominating this season.
I think the biggest surprise will be ... Williams! Their package will surprise everybody!
And the biggest dissapointment is obviously the reliability of the Ilmor engines, once again.
Biggest Surprise: Honda's consistant resaults
Biggest Dissapointment: The debate about the V10r going on, and perhaps getting some drivers disqualified.