Ever since I got my MacBook Pro, I can't stand mice. I used to hate laptop trackpads, but Apple's trackpads are totally different than any other trackpad. They're responsive and capacitive, and of course there's multi-touch. The Magic Mouse doesn't even support the most basic functions of OS X.
I love the design and feel of the Magic Mouse, but I find that other mice (Logitech) are still more comfortable and useful, even though they're ugly and their scrolling is crap (line by line as opposed to pixel by pixel). I think that Apple put themselves in a situation where the mouse is no longer a desirable input device, and I agree.
I do find it less tiring to use a mouse for doing lots of dragging, such as video editing, or organizing files (lots of drag & drop). The only thing trackpads can't currently do properly is drag and drop: You either need to enable the annoying software tap-drag, which introduces a small but annoying lag to every click, or you have to click the trackpad but then you have to use two hands to drag. With a mouse, dragging is super simple.
However, OS X requires less and less dragging: No more scroll bars, iTunes volume control can be "scrolled" left and right without having to drag it, the introduction of Cut and Paste (finally) in Lion reduces the need to drag files from one place to the other, etc... so this problem is getting less and less important, but still exists.
I use a Wacom Tablet for precision work, my trackpad for anything that requires scrolling (browsing) and a mouse for video editing and gaming. But if you're a gamer, you don't want an Apple mouse anyway, since it lacks buttons and notch-scrolling (useful for precise weapon selection).
I think the only "serious" place where a mouse is definitely required is video editing, as you do lots of dragging, and pointing and clicking.
