Just to whet your appetite...
And here is an incredible video of Lovejoy- a sun-grazer, like Comet ISON- surviving its close encounter with our nearest star:
Meanwhile, for those of you who have either forgotten or somehow missed them, here, respectively, are shots of the last two Great Comets visible at their peak in the Northern Hemisphere, Comets Hyukatake (1996) and Hale-Bopp (1997).
And here is an article on the Great Comet of 1680, whose orbit is similar to ISON's.
There is no telling, of course, what PanSTARRS or ISON will actually look like. One or both might even be duds, like Comet Kohoutek (1973) or Comet Austin (1990). But these pictures will give you an idea of what might be in store.