Mine never had any problems, but I ebayed it because I never used it properly. If you're someone that uses a filofax or similar a lot, you may just find it useful.
I had a palm. The software on the device is simple but great. Devices with portable versions of Windows on it have more features immediately available (more support for different file formats, etc.), but the interface isn't as good.
If you're in need or organising your life and need something with a calendar, todo lists, etc., then you may benefit from one. Make sure you get a decent case too -- you don't want to damage the screen.
Personally I also found mine too bulky and didn't like carrying it with me so never did. I also now like the GTD methodology (google it if you're interested, it's got a bit of a cult following), and while a PDA fits in here, so does some notepaper and the calendar on my phone (that I have with me at all times anyway).