Interesting, the article slams it for fit and finish (manufacturing issues) rather than functional issues. I suspect this will be the biggest thing people learn using kickstarter, manufacturing is not straightforward as one might hope.
It criticizes both aspects, although it spends less time on the functional issues, presumably because it really doesn't do that much. Here's the paragraph dedicated to the problem with the functionality:
'One benefit touted by the Touchfire creators is that you can rest your fingers on the keyboard without accidentally producing a string of nonsense. The problem with that statement is that it’s not true. Especially when typing on an angle, my resting fingers easily made it through the thin plastic layer to create fun words like “eoran” and “nadskj”.'
It also says that it's "pretty gratifying" to type with, so it seems to be a mixed bag, functionality-wise.