I saw a reduction of about $85 in my net pay due to the SS tax and the increase in health insurance premium. $85 x 26 paydays = $2,210 ($184 a month) in lost income for 1 year.
That's one way to look at it. The other way is to realize that you gained $85 per paycheck over the last 2 years, which may not have happened if the payroll tax holiday never took place.