The problem isn't that TouchFLO 3D is badly designed: it's that it's sluggish and incredibly frustrating to use. Sure, we like that HTC has tried to make it easier to access features like music and photos. Sadly, the overwhelming reality of TouchFLO 3D is that it's far too slow compared to the iPhone's interface.
What makes matters worse is that the Touch Diamond's screen responsiveness and the TouchFLO 3D interface simply don't mesh together in a smooth and reliable way. At times, you feel like you're dragging mud rather than pushing an ice cube. We often found doing the simplest of tasks, such as dialling a number or text messaging, tiresome.
If you're wondering how the text messaging interface fares, don't get excited. HTC has implemented a variety of finger-friendly, on-screen keyboards, but there's a problem. In certain areas of the phone in which there are multiple fields, particularly areas that haven't been meshed well with the Windows Mobile interface, the HTC keyboards cover up the your typing area so that you can't see what you're doing.
While the Touch Diamond might look similar to the iPhone and have a few of the same interface features, this is definitely not an iPhone. The Touch Diamond looks slicker than any Windows Mobile device out there, but it's still very much a Windows Mobile experience. Every now and then, you're launched back into the familiar but fiddly Windows Mobile interface, away from TouchFLO 3D, and that left us deeply disappointed.