Looking at both the HD2 and HD mini, it's safe to say the resemblance is uncanny. And if the mini moniker isn't a clear indication, then holding the HD mini in one's hands would make it even more obvious. Its overall dimensions of 103.8 x 57.7 x 11.7mm puts it squarely in our palms as a perfect fit. Neither overly large nor too small to handle, the HD mini also had a good amount of balance with its 110g weight.
Other than obvious differences in its screen size, both units share the same frontal layout. A row of touch-sensitive panels, most of which are familiar sights, lies just below its 3.2-inch capacitive touch screen. We have the Call/End buttons at the edges, and nestled in between are the Home, Start and Back buttons. Each panel is given adequate spacing, and aren't too spread out as compared to the HD2's wider dimensions. The only physical buttons would be the volume control at the left profile and the power button at the crown. The 3.5mm audio jack is located just next to the power button.
Similar to the HD2, the HD mini will only see fingerprint smudges on its front. What differentiates it from its larger sibling is the removable housing, which covers the sides and rear of the device. Theoretically speaking, one can customize the HD mini with different patterns for the housing. HTC hasn't released any customized housings yet, so the next possible candidates would be third-party accessory makers. In fact, we've actually seen a clear plastic backing based prototype from HTC and it certainly makes the phone an interesting conversational piece (literally speaking too).
Removing the housing is relatively easy, and once you do, you can swap in the microSD card without powering down the device. While the exterior sports a solemn black look, the internal is splashed a bright yellow backing, including the 1200mAh battery that blends in.