Grading him against what? or whom? All assessments must have a standard. That's the problem with all the people giving him grades, they all use a different rubric.
Was he able to turn the economy around? He's done more in 100 days than W did in eight years, but then one step forward is better than a million steps backwards.
Did he get as much legislation passed as FDR? No, but FDR had more months to write the legislation and get his ducks in a row, he wasn't inaugurated until March back then, not January. His first hundred days ended in June, and there's always a flurry of legislation passed just before summer recess.
Still it does make me think of school and if I follow that grading analogy a hundred days would be the equivalent of the very first grade of the very first week of school. He has four years, the final report card won't come out for quite some time. Granted no one wants to start the school year off with a failing grade, but it doesn't mean you'll fail the course. Getting an A on the first grade is also no guarantee that you'll pass the class.
I liked Madeline Albright's comment where she compares this to the first hundred yards of a mile. (I was a miler in high school and college, she's talking my language) The first hundred yards of a mile only gets you into the rhythm of the race, it doesn't determine the outcome.