I am (was) a mobile developer and my favorite app that I ever wrote was a TV guide for a (very) large ISP/cable company. Unfortunately, it was for Blackberry in 2010 just as they were in their death throes. The most common response from people who tried it was "how is this even possible on a Blackberry?" Blackberrys were actually extremely powerful devices, but it was an abysmal platform for developers; sometimes just testing out a one-line code change took 45 minutes, or maybe wasn't even possible at all and I had to go home (come to think of it, maybe that made it a great platform for developers).

An under-appreciated negative about them was that the most common devices had 16-bit color (RGB565 which used 5 bits each for red and blue and 6 bits for green - I have no idea what made green so special) which made everything look washed-out and pukey. That scroll wheel was fantastic, though. Really allowed you to do precision control despite the tiny screen, something that just isn't possible on today's touchscreen devices with fat fingers.