We made a decision to go with a handwritten font for that reason. It is gratifying to cross items off a list, putting pen to paper, so we tried to mimic that with the font and swipe action. That said, we totally understand wanting to use a sans serif. Helvetica and other options may be in a future release.
I think the suggestion was to use the sans-serif for the heading. This makes sense because you're not writing "Today" — that's part of the interface. Same as you're not writing "May 2012" on the calendar.
The large, handwriting typeface works well for the list items as it makes you focus on it, but the "Today" heading should be different if only to clearly separate the middle section as your "list". Overall terrific design though.
