One of our commenters said the real size comparison they wanted to see was the HTC Touch Pro vs the HTC Touch Pro 2, which seems a fair question, the one being the successor to the other.
Unfortunately I have neither device here, but quickly mocked up this graphic showing the relative sizes.
The HTC Touch Pro is 51 x 102 x 18.05 millimetres, while the Touch Pro 2 is 59.2 x 116 x 17.25 millimetres. That makes the Touch Pro 2 a much larger device, 8.2mm (1/3 inch) wider and 14 mm (0.55 inches) taller. In fact, the device is even slightly taller than the HTC Kaiser (59 x 112 x 19mm). Of course of the 3 devices the Touch Pro 2 is the thinner, at 17.25 mm, but one does have to wonder about the range of appeal of such large device, even for business users.
Of course the big 62.1 x 115.5 x 12.3 iPhone 3G does prove that if you make a device interesting enough the public is willing to overlook trivial things such as the size of the device.
Of note also is the curved design, with sloping sides, which does a lot to improve the hand-feel of the device and gives the impression that its a lot smaller than it really is.
Is the Touch Pro 2 too large? Let us know in the comments.