It's a nice piece of hardware; I like the fact that it contains so much in such a small device. I have no problem with the fact that there's no backlight on the screen, since that makes the battery last longer. I like the software on the device; it contains everything I need in a PDA.
But the fact that it's hard to copy anything from my PDA to my computer's hard disk ruined everything. The G.Mate Yopy YP3000, as it came out of the box, could not easily be connected to a Linux system. When you did want to connect it, you would have to exchange the usb module which was on the device with a different one you had to download from the web; but that gives you a chicken-and-egg problem where you have to exchange a module to be able to communicate and exchange that module. Alternatively, there was a (non-supported) usb module for a desktop system which would allow you to read and write from/to the Yopy, using its out-of-the-box modules; however, there were problems when trying to do that on a fairly recent system, since it, uh, panicked your system.
Luckily, G.Mate seems to have gotten that message. According to what I've heard, their newer models, such as the YP3500 and the YP3700 can, in their default configuration, communicate with a GNU/Linux desktop using the usbnet system; and instead of using a proprietary format, the YP3500 and YP3700 would use a MySQL database containing the PIM information; this allows you to synchronize the information with different databases on different systems, provided you issue the correct 'grant' commands inside the MySQL database.
For that reason, I have modified this page. It used to give an enourmous rant; but since the information is no longer accurate with the newest models, it is no longer fair to do this.
If I ever have to buy a new PDA, it might be a yopy again.