Henrik Nilsen Omma have had a look at the general usability of the touchscreen-enabled GOK!
Read it here at the Ubuntu wiki:
Does GOK have any users? Seriously. Or does it only ever get tested by it's developers? It certainly has many potential users. Those who currently have to pay large sums for a full-featured on-screen keyboard on Mac or Windows. I would actually recommend making Windows and Mac ports. This would see GOK being used by real users, providing useful feedback, not to mention an invaluable free service to those users.
It is a concern that accessibility for Linux is such a niche topic that it doesn't receive enough testing and development. This seems to be especially true in the case of GOK. Gnopernicus, Dasher and GOK are mentioned as answers to the questions of whether we have AT features on Linux, but do these products really meet the needs of users? At the moment I fear it's more of an alibi.