I have been using mine for a few weeks now! I was using an XDA Orbit 2 which is a great phone! I love my Diamond, even though it has some battery issues and can be a bit sluggish on the TouchFlo 3D also no expansion slot but I still love it.
The Screen is amazing, web browsing is fantastic, because the screen is so clear you find you don't have to zoom in as far or not at all sometimes. You can read goggle searches without zooming! when I turn on my Orbit now the screen looks so low resolution its wierd!
The accelorometer also comes in very handy for rotating pages and pictures, there is even a great little game which you use the phone to control a ball.
TouchFlo Looks great, you really don't need to use the stylus at all now, it feel nice sliding along to each tab, the weather tab is cool with animated weather icons and rain that apears on the screen which is then wiped off by a little wiper blade! really nice touch!
It is very fingerprint prone but as long as you put on the provided screen protector there is nothing to worry about, it all wipes clean!
Another cool feature is the light sensor which when the backlight is set to auto, it will automatically dim or brighten depending on the ambient light, hence if its really dark it will dim the backlight so you don't burn your retina's!! and the opposite for bright sunshine!!
The other thing to mention is that the signal strenght doesn't seem to be as good as my Orbit 2, but I haven't had any real issues with that! If you live in a bad area then this could be an issue!
I only give this 4 Stars due to the lack of expandable memory and the fact it only has a 900mah Battery. If these were better it would be 5 Stars from me!!