I'd advise against the Mighty Mouse.
A few minor things about the mouse...
1) Right click requires you to lift your left finger when clicking. Also, depending on how you hold your mouse, you might get mislicks. You'll probably get used to it, though, so it's not a biggie.
2) I don't know about other users, but I never use the sqeeze function or the scrollball button. I use screen corners, and since you're using a mouse anyways - screen corners are easier and (for me) faster. Personal preference, probably.
3) 360 scrollball, but it only does vertical and horizontal scrolling. So no diagonal scrolling.
If we ended here, everything else would be all right. If I had to rate it on a scale of 5, I'd give it a 3.5. Nothing revolutionary, but nifty, sleek, and the right click is useful once you get used to it. I like having a scrollball, too, because I read alot of online text.
However, there's two things that make me reconsider the Mighty Mouse more, as they are more of actual problems - not based on preference or getting used to things.
The first is more minor. Sometimes the button doesn't go down. It's happened now and then for me, and I don't know why, exactly. Maybe it jammed down. It's not really major, though, because I've fixed it just by picking the mouse up and setting it back down.
The second problem is a huge problem, and what is big enough to be a product defect. I don't know if it's an isolated incident of a bad batch of Mighty Mice, or if it randomly happens now and then, but the scroll wheel has problems. After some time, you might find that your Mighty Mouse will refuse to scroll. It's not a software problem, because I can feel the scrollball actually not giving the same tactile feedback as before. It might only allow you to scroll up, or scroll down. I don't know about left and right, because I almost never horizontally scroll. Several members on MR, myself included, have had this problem. I'm definately vexed by it, because my main reason for having a mouse is for the scrollball because I'm about as fast with a trackpad as with a mouse. With the scrollball messed up, I might as well toss the thing into the garbage. I have noticed, however, that the scrollball sometimes "clicks back" into place. I'm not sure about the anatomy of the Mighty Mouse, but there have been times that the scrollball gets set back to where it's supposed to be, and I feel the normal tactile feedback and the mouse works fine again.
With this durability/build quality problem, I'd give the Mighty Mouse 1 out of 5 stars, and that's pretty generous, and only because I like its glossy white sheen.