When I purchased the Magic Trackpad, I was really hesitating as to whether to buy the Trackpad or the Magic Mouse. Both were the same price (roughly), however I think I made the right decision.
Firstly, the Magic Trackpad is essentially like an iPhone screen. All the multi-touch gestures on the iPhone are integrated into the Magic Trackpad. You can do anything you want, even pinch to zoom and turning your fingers to rotate pictures in Aperture or iPhoto. This is really brilliant, as it brings one of the best bits of the iPhone to the Mac. Furthermore, the Magic Mouse has really limited gestures, and is nothing like an iPhone screen.
The other thing I like about the Trackpad is how wide it is. You have room to do all the gestures, and when compared with the Magic Mouse, for example, you realise the difference. On the Magic Mouse gesture wise, everything is cramped, so it makes a real difference.
The final thing to say is that the Magic Trackpad is the future. The mouse is slowly disappearing, and multi-touch is the future. The Magic Trackpad therefore is the future, and the Magic Mouse, even having some limited multi touch capabilities, is more a less the past.
Apple rarely make disappointing products (there have been some though), and they, in my opinion, certainly have not disappointed with the Magic Trackpad. which really is the way to go. Needless to say, a 3 year old could have installed it.
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