I have a DIP Pocket PC, which is *exactly* the same as the Atari Portfolio (even to the "Atari" key), except that it has different badging, and 512K of memory. The Portfolio (and a number of other palmtops) was designed by DIP, although it is marketed by Atari.
If I was going to buy another palmtop tomorrow, I would probably buy an HP95, merely because of their popularity, and hence the wide availability of software, in direct contrast to the Atari. Also, the Atari has proven not to be very reliable, and survives battery changes very poorly. I have had to restore everything from backup several times.