I have been using a Mighty Mouse for about a month now which I got as a leaving present from my kind colleagues, so I thought I'd share my impressions. I intentionally waited for a few weeks to allow myself time to get used to it.
Up to now, my mouse of choice has been a Microsoft Wheel Mouse Optical, a two-button mouse (three if you count the scroll wheel). I really like the shape, the feel of the buttons, and its durability.
One of my first thoughts when I started using the Mighty Mouse was that the button was too hard to press. I searched for a switch to adjust the firmness, as I had seen on the Apple Bluetooth Mouse, but no luck. I got used to it eventually, but initially this caused my hand to get tired quite easily. It's a shame they don't have the adjustment feature across all their mice. I can't see any obvious reason for not including it.
Another reason why my hand and wrist felt tired was that I was used to resting my hand on my Microsoft mouse, which is quite high at its highest point. The Mighty Mouse is much flatter. Also, I think because the whole surface forms the button, I felt hesitant to put too much weight on it.
What people probably wonder about most is how well right-clicking works. At least I did. As you may have read elsewhere, it requires you to actually lift your index finger off the surface. As long as your finger touches the area to the left of the scroll ball (for the right-handed setting), any clicks are registered as
primary clicks. I wasn't sure if this would be a problem, because I didn't actually know whether or not I usually lifted my index finger. Well, it turns out I didn't. On other mice, I was just applying more pressure on the right side. I wouldn't say that getting used to Apple's prescribed technique was hard, but it did take some conscious effort at first. I still fail very occasionally, even after four weeks of using it.
The side buttons are also interesting. You squeeze them to activate them, but although they give slightly, there's no tangible click. Instead, you get feedback in the form of a clicking sound from the built-in speaker. This sounds very natural and I find it actually gives you the illusion of feeling the click as well. It's only when the mouse is disconnected and has no power that you're sure there's no physical click. Of course, this whole concept breaks down if you are in a noisy environment or if you are deaf. Also, the buttons really give only slightly, so I tend to apply quite a lot of pressure, which is tiring.
I have to say I don't really use the side buttons. The main reason is their positioning. When I hold the mouse in a natural position, my ring finger is on the side button on the right, but my thumb is just behind the left one. So to get a grip, I either need to move forward my thumb (and therefore my wrist) or hold the mouse slightly angled to the left. This is kind of crappy, since it seems like an obvious problem and shouldn't be hard to fix (just make the buttons wider, spanning further back).
On to the Mighty Mouse's other big curiosity: the scroll ball. Let's look at traditional, vertical scrolling for now. In a nutshell, it feels great. Scrolling is much smoother than on other mice, because it seems to have a higher
resolution. Scrolling produces soft clicking sounds, which are artificial like on the side buttons, but here the illusion of tactile feedback is even more convincing. Also, you have to apply a tiny bit of pressure while using it, so if you touch it very lightly and move it, nothing happens. I guess the reason for this behaviour is to avoid accidental scrolling when you brush over the ball while moving your fingers. Apple did an amazing job of tuning the threshold for this so you probably will never notice.
What I was looking forward to most in this mouse is the idea of being able to scroll horizontally without having to hold the Shift key. Unfortunately, the result here has been disappointing. It works, but it doesn't work very well. The problem is one of ergonomics. To scroll vertically, you can use about an inch of your index finger's length to move the ball, from the tip of the finger to just behind the first joint. This not only gives you a fairly good range, but also very fine control. In contrast, when scrolling horizontally, only a very narrow part of you finger can make contact with the ball, so you have to keep
scrubbing to scroll longer distances. That could be fixed by accelerating horizontal movement more than vertical, but the other problem is that horizontal scrolling is very hard to control. This is partly due to the limited range, of course, but also because your finger
sticks to the shiny surface of the mouse on either side of the scroll ball. When you apply more force to overcome that stickiness, your finger suddenly sweeps across the ball much faster than you intended, resulting in very jerky movements. It can be quite frustrating.
I can think of two possible improvements. One is to make the surface rougher, at least around the scroll ball. The other is to expose a bit more of the sides of the scroll ball, by making the surface of the mouse slightly concave at the top.
The other thing you can do with the scroll ball is click. The thing to note here is that it's not the depressing of the scroll ball which causes the click, but pressing the whole mouse down while your finger is on the scroll ball. In fact, the same pressure detection used to activate the scroll ball when scrolling also seems to give the condition for a
middle click. This means that a middle click doesn't actually feel any different from a normal click, which can be a bit confusing. But at least you don't have to lift up your other fingers in order for it to work.
So the Mighty Mouse delivers many novel ideas, but how well these work is quite a mixed bag. Vertical scrolling is the only real winner. Once you're used to this one, traditional scroll wheels will feel clunky and primitive. Although some of the other features, like horizontal scrolling, are potentially useful, others feel like they're just there to make the mouse as unconventional as possible.
Innovation is appreciated, but not just for the sake of innovating.