When I wrote the input methods section of SPB Tips and Tricks for Pocket PC I tried a bunch of input methods and wrote my impressions of them.
Recently I have been running with just the plain old input methods that are default on the Pocket PC. These are all really slow and really painful to work with. This is the reason why James has struggled with the Pocket PC - it is not efficient out of the box for data entry. In fact it is easy to get frustrated after a little use and give up.
After suffering a little frustration, I went back to Fitaly from Textware solutions.
I've got to say - the difference is huuuge. Sure the learning curve is steep, but the ease of entry is massive. Instantly I went from a frustrating 10-20 wpm to 30-50 wpm. Like I said - the learning curve is a little steep (especially to start with) but once you've got it - you cant easily go back.
I've now purchased the upgrade (I had version 3.0 - without VGA support) and parted with my money - but I think it was worth it.