Most everything I do is with the stylus, though I m sure the buttons have their place. The ease of expandability is a huge plus. Just pop in a CF type memory card, and you have instant data storage expansion. Just copy data to the storage card in the Sync manager, and you re set. You can even take pictures with the DC290, save them on the CF card, and view them on the Casio E125.
Processing speed is great.
A fairly large map of Chicago proper loads in about six seconds, with zooms showing up quickly. My only real complaints are the cradle and a GPS system. The cradle does not seem to hold the unit in place snug, and you have to press down hard and make sure the connection is made before any charging or sync up is done. As far as a GPS, I ve read about the Pharos unit, and a few others. Kind of steep.