We have to point out, however, that you will need some sort of solid surface to use the left/right "click" features. The entire trackpad doesn't actually depress. There are two small bumps beneath the front of the pad, and when you press downward, those bumps actually click up into the pad to register a left/right click. That said, you can always just tap your finger for left click and two-finger tap for right click, so you still have an option there. Apple includes two AA batteries which power the Bluetooth module within; while we have not used the trackpad long enough to seriously comment on long-term battery life, it seemed to only drop a percent or two after a few days of normal desktop usage.
Onto usability and performance. For starters, we should mention that the very latest version of Mac OS X is required. Yes, required. OS X 10.6.4 must be installed on your Mac, along with a ~75MB update that can be downloaded from the company's support site. The pad also works with Windows machines if you're willing to do some digging, though the functionality is stripped to simply moving your cursor around and two-finger gestures like scrolling; frankly, we can't recommend this for Windows users with so many other fully-featured alternatives on the market. But on the Mac side, the settings are rather in-depth and advanced, and it's those special features that might make you consider this device over a traditional mouse.
Once you have updated your system to 10.6.4 and installed the Magic Trackpad update, installation is a breeze. We rebooted our machine post-update, turned on Bluetooth, pressed the power button on the pad and told our Mac to setup a new Bluetooth device. It took about 10 seconds for the pad to be found, and once it was paired, we headed into System Preferences where a "Trackpad" icon greeted us. This is where most of the "Magic" in the Magic Trackpad happens. Users can adjust tracking speed double-click speed and scrolling speeds, while you can enable Tap to Click, Dragging, Drag Lock and Secondary Click (for left or right corner). Two finger selections get even more interesting: Scroll (with or without Inertia), Rotate, Pinch Open & Close, Screen Zoom and Secondary Tap. There are even options for Three and Four Finger tapping: Dragging/Flip through, Swipe Up/Down for Expose and Swipe Left/Right to Switch Applications.
In general, we're looking at this review as a way to judge whether or not the Magic Trackpad is a) a good replacement for your desktop mouse and/or b) a good replacement for your travel mouse or a good secondary control method for the on-the-go computer user who currently doesn't have one. Just by reading above, you'll notice a slew of things that your average mouse can't do. But these aren't necessarily things that your average high-end, third-party mouse can't do with a bit of macro work and assigning certain commands to certain buttons. It's obviously far more capable than a Mighty Mouse, but those with higher-end multi-button mice may already have some of these commands mapped to key shortcuts.
There is no two ways about it: there's a learning curve to the Magic Trackpad. Even those who use a newer generation MacBook as their primary machine will have to get used to how this pad operates. It's not difficult to grasp, per se, but using it perfectly takes some time. Most computer users have been controlling their desktops with mice forever; suddenly, you're forcing your mind to translate a trackpad into a desktop controller, and it takes a few hours just to get the hang of it and stop cupping your hand as your reach for your "mouse that's no longer there." For us, the size was just about perfect. It's notably larger than a MacBook trackpad, but it didn't seem "too" large at any point. Our main gripe about the layout is that the two buttons underneath that depress for left/right click were too low to the bottom, so pressing the top took more effort than pressing at the bottom. Not a tremendous amount, but enough to become bothersome at times.
The surface of the pad feels exactly like a new generation MacBook pad. It's the same exact tactility, which is a definite positive. It's easy to touch, it's easy to move around on, yet there's a feeling of traction that you don't often get with purely glossy trackpads. We did yearn for the maximum trackpad speed to be a bit higher, but for most users it'll track plenty fast. Using the pad, once we actually became used to the idea on a desktop, was simple. It's effectively exactly like using a MacBook trackpad. What's most interesting about using the Magic Trackpad on a desktop is the things that you can incorporate into your workflow that you previously weren't using. Swipe to open Expose? That's handy! Definitely more handy than pressing an "F" function key. Three fingers to drag/drop windows? Certainly easier than clicking, selecting, then holding and dragging. And in general, using a surface of just 5" versus having a mousing surface that's quite a bit larger is preferred. You never have to wonder if you left your mouse sitting too close to the edge of the table before grabbing and starting a task; the trackpad surface is always the same size and the position is wherever you make it. That's a big plus for those cramped for space.
The gestures are really what set the Magic Trackpad apart. Adding gestures to your workflow can really speed up how you navigate within your desktop environment; if you're constantly zooming text in various Web windows, the pinch/zoom gesture is so much faster than moving over to your keyboard and pressing a two-key combo to accomplish the same thing. When viewing photos, the inertial scrolling (click and drag on a map in Google Maps, then let go as you're dragging if you've never experience inertial scrolling) is a great addition, and makes for less work on the end user.
Again, all of this has been possible via a MacBook trackpad, but how many computer users do you honestly know that integrate this into their desktop workflow? Most people have separate workflows for their notebook and desktop, and the Magic Trackpad is a great way to seamlessly connect those two for Mac users.
Performance was near-flawless. Tracking was extremely precise, and the pad recognized even the softest of taps and the most gentle of swipes. Apple has really nailed the input recognition; never did we have a gesture go unnoticed. In fact, the recognition is so good, that we occasionally would swipe up without actually meaning to, and thus we would enable Expose. But it's easy to compensate and avoid those errors once you get used to using the trackpad on a desktop, and we were never annoyed by the performance. Apple has managed to convert their world-class trackpad performance on the MacBook line into a standalone peripheral. After constant use, we actually found the trackpad speeding up some areas of our life, but slowing others. We get the impression that the Magic Trackpad will greatly help those that sort through multi-media often (and HTPC users who control from the couch), but those who find themselves clicking on small cells or areas (such as in an Excel sheet) will most likely prefer the added precision of a mouse. If you practiced enough with the trackpad, you could probably get yourself to that level of precision, but if your mouse does the trick, why try to reinvent the wheel?