From John Siracusa’s epic 19 page review of Lion:
The trouble is, the new iCal looks so much like a familiar physical object that it’s easy to start expecting it to behave like one as well. For example, iCal tries very hard to sell the tear-off paper calendar illusion, with the stitched binding, the tiny remains of already-removed sheets, and even a page curl animation when advancing through the months. But can you grab the corner of a page with your mouse and tear it off? Nope, you have to use the arrow buttons or a keyboard command, just like in the previous version of iCal. Can you scribble in the margins? Can you cross off days with a pen? Can you briefly fold the page upward to peek at the next month? No, no, and no.
At the same time, iCal is still constrained by some of the limitations of its physical counterpart. A paper calendar must choose a single way to break up the days in the year. Usually, each page contains a month, but there’s no reason for a virtual calendar to be limited in the same way. When dealing with events that span months, it’s much more convenient to view time as a continuous stream of weeks or days. This is especially true on large desktop monitors, were zooming the iCal window to full screen doesn’t show any more days but just makes the days in the current month larger.