5-series 3 years ago and now switched to a 5mx. There's simply nothing on the market that even comes close to it, and I've tried lot's of different devices. I say more I am writing my master's thesis on my 5mx. The keys are a little cranky, missing sometimes and double striking at others. The screen can be hard to see, even with the backlight.
Fonts can be too small.
It IS a full personal computer, fast and elegant. I am addicted to mine. This is the device for those who think Palm got it wrong. I used Psion series 5MX and was very satisfied. I thought I could never leave it at home.