I've been using Textmaker on the Z5500 as my main word processor for a week now, and am impressed with the quality. I haven't had a single crash, and it's handled every file I've thrown at it beautifully (except for the problem with bullet points in MS Word files, but that is a problem with my desktop Linux word processors as well). Actually, it's the first time in my 12 years as a PDA owner that I don't feel I'm using a dumbed-down word processor.
My only real complaint at this time has to be the slow screen redraw when editing large text files. This could be due to the slow processor in my Zaurus, of course, but it definitely limits my typing speed. I'll keep on testing Textmaker for the duration of the beta period - by October 15 I'll know if the redraw problem is serious enough to prevent me from paying € 49 for Textmaker. :-)