I think t3_slider is being overly harsh... there's lots of great software for the Palm, although you do struggle these days to find anything up to date that's based on the old motorola (er, freescale!) dragonball 68k based CPU. The 3rd party PIMs on palm are truly excellent, I use Datebook5.
I must admit I've never tried to use my Z as a PIM, mainly because I tend to tinker too much with the Z and never settled down long enough to be confident that I could always access the PIM apps... I long since ceased playing with my T3 and so it's pretty stable.