Having owned both a 200LX and a Psion Series 5 (and other handhelds), I wish I could justify buying the Gemini. Unfortunately, I already have too many bits of tech I don't use regularly to warrant another to go on the pile.
The keyboard is good, for the size it is (whole thing is large phone size). I have a Psion 5, and the Gemini keyboard is pretty much an exact copy, but better.
I feel like there's 2 kinds of keyboard modalities - thumbs (loved my Blackberries) and touch-type. The Gemini is just a bit too small for touch typing, and is too large for thumbs. It's still very cool.
I typed a couple of blog posts on it, but wouldn't want to do more than that. Since then it's been gathering dust.
I'm planning to eBay it soon to very-slightly-offset a Pocket Reform. From the pictures believe that the Pocket Reform is just large enough to be a touch-typer.
Totally different kind of device than the Psion Series.
Draws an order of magnitude more power.