
What makes the Magic Mouse so much better than its predecessor, the Mighty Mouse, is, well, everything.
In the previous rendition Apple added sensitivity to the click "buttons" and eliminated the actual need for an independent button for each side of the mouse.
That same philosophy carries over to the Magic Mouse with the entire device being really a single clicking button. The sensitive technology is still built in and though there are a few little hiccups that do carry over from its Mighty brother, the device overall is much better built and with a significantly more redefined sensitivity system.
Let's talk about the little issues that do carry over from the first generation all white mouse. For starters, as I've mentioned, there is only a single clicking surface. The mouse uses touch sensitivity to identify the intended task, e.g. the left or right click function. The one drawback of this - if it can be defined as such - is that for right-handed users you must raise your index finger in order to right click with your middle finger. If you don't the unit cannot distinguish your command and if anything will usually default to the standard left button click.
The mouse is ambidextrous programmable and because of its symmetrical design it is identical in use for both the left and right and, just tell the program (under system preferences) your desired orientation.
The mouse loses the twin side click surfaces found on the previous mouse. My opinion on that is - Thanks! They always activated undesirable features of the OS because I would accidentally grab them while working on a project or surfing the web. I finally deactivated those controls in the preferences menu. If you liked that feature, more power to you, but if you want the Magic you have to sacrifice that feature of the Mighty.
Though the most notable feature of the new mouse is the touch sensitivity, which I will discuss in a moment, one of the best features that I think new users will notice is the improved bottom design. The bottom is now almost entirely aluminum and smaller. The on off switch is very simple and the green light gives a clear indication of the connection - or lack there of. All of these nice design features out of the way however, and you'll notice what I think is one of the best features of this mouse - the sled base.
The previous base glided, and sometimes stuck, on a glossy plastic ring that ran the circumference of the mouse base. This would easily get covered in dirt and grime and you'd have to scrape it of with you nail or other hard instrument. Even then it never really "glided" to me.
The magic mouse rests on a pair of sled-like skis. These provide much smoother motion in my opinion and are better suited for extended use.
I have not idea if Apple redesigned the optical guide or not, but it seem more accurate and responsive.
Finally, we come to the touch sensitivity feature and the best feature not on the Magic mouse at all. The most improved feature of the mouse is without question the track ball. The previous version did let you do 360 degree navigation, but the ball would easily become dirty over time and it was virtually impossible to clean because Apple didn't make it user cleanable. I had both a wired and Blutooth version of the Mighty Mouse and both of them ran into this problem. One of them - the wired version - finally quit scrolling up all together.
The Magic Mouse eliminates this problem by incorporating Apple's touch technology to the mouse surface. Just like an iPhone or iPod Touch or the newer track pads on the MacBooks, the surface can respond to finger gestures. The sensitivity works effortlessly and is superb in both internet browsing and visual applications like iPhoto and Photoshop.
You will likely use it most often for scrolling up and down internet pages and for browsing through photos (left and right flicks), but you can also navigate around a large page or photo by simply directing your finger along the top of the surface. In addition, you can two finger flick to progress forward and back through pages in a single navigation window (i.e. you can two finger flick from right to left to view the previous page instead of clicking the "Back" button). You can also use the two finger gesture in other applications, but I find it really unnecessary at this time. Also, depending on your finger dexterity, you might actually find this task slightly complicated. Unlike a laptop track pad that stays still, allowing you to raise and lower your hand as a whole, you have to hold the mouse while doing it. I typically control the mouse with my thumb and little finger with my ring finger resting. When I try to two-finger flick, it is not exactly comfortable and the results can be interesting - depending on use - if you're not great at it like me.
So, if your a hand gymnast then you'll love this feature, but the two-finger flick is not my favorite part of the mouse and I rarely use it. Overall though, the scroll functionality is awesome, though sensitive and can cause unwanted moving in Photoshop at full screen or on the web.
In summary, the Magic Mouse is a more than worthy upgrade from the often problematic Mighty Mouse. The setup and functionality are very easy and the touch interface is incredibly useful and leave no more worry about dirt getting in the guide toggle. If you prefer more of an organic design with a higher rise to rest your palm or are a gamer who wants lots of buttons or a massive track ball, then look elsewhere. If you want a simple, elegant and well designed mouse that is likely to be maintanance free then the Apple Magic Mouse just might be for you.