I actually have pretty fond memories of PalmOS PDAs. The hardware was very nice, but they were held back by the resistive touchscreen and dependence on a stylus for input. I never used a Treo but it felt like this was Palm trying to copy BlackBerry by adding a physical keyboard.

Edit: There were also the limitations of that era that held devices back in general. WAP internet[1] was awful, but most mobile services were too slow for much else.

[1] https://en.wikipedia.org/wiki/Wireless_Application_Protocol