I'm R1K010 - generally stable, occaisional reboot/glitch requiring battery pull/abnormality. My 4th Z1010, my first that has survived a reasonable amount of time. It's as good as a Sony Ericsson gets in my experience.
Well, I've had this one for some time now, but I'd understand if they hadn't made any more since. Frankly it's good enough, and the phone's surely too old for them to continue developing the software for it.