First off, the Sidekick 3 is really just an evolution and enhancement of its predecessor (just as the SKII was with the original Sidekick). It's about 20% smaller (it's definitely more pocketable), and finally has Bluetooth, a memory card slot, and a better camera,
Just as the Sidekick II was with the original Sidekick, the Sidekick is at heart just an evolution and enhancement of its predecessor. The big improvements? Bluetooth, a memory card slot, a better camera, more memory, a music player, and a trackball. There haven't been any major changes in the UI (mainly a few tweaks here and there), and you may or may not like the new keyboard (we liked it, but you'll just have to try it yourself and see), but the biggest disappointment is the display, which is still a paltry 240 x 160 pixels and still looks sorta washed out to our eyes.
[Thanks to Eric Lin at PhoneScoop for hooking us up with the side-by-side shots)
We didn't have high hopes for the trackball, but so far it's worked surprisingly well and makes navigating the UI a breeze.
1.3 megapixel camera.
The keyboard is a bit more tactile now.
It's sort of a bummer that you have to remove the back casing to insert or remove the memory card, but at least you don't have to pop out the battery, right?
Like we said, the UI on the Sidekick 3 isn't radically different than that of the SKII.
The biggest change is probably the addition of a music player. It's fairly easy to navigate, and the audio quality is decent, though not spectactular.