I think an important part of what made Graffiti so effective was the fact that you had access to a complete range of alphanumeric and punctuation characters without any need to switch modes. There were actually quite a number of onboard programming tools for Palm devices, so I could easily write little scripts in BASIC, Forth or OnboardC to pass the time or quickly try out an idea. It made the device feel more like a computer and less like a toy.

Most of the touch-based keyboards I've seen on modern smartphones perform acceptably when you're composing a message made out of English words, but you can just about forget coding on one. Even Lua, which is well-known for having a sparse syntax mainly composed of alphabetical keywords, is torture on an iPod Touch.