IHMO the biggest problem with smart phones is durability when dropped. Something extra for a case is needed to take the initial impact of a drop.

I tried the Otterbox for my Treo 650. It makes the package much bulkier, diminishes the sound quality for both parties, and hinders the usefulness of the touchscreen by making hampering the touchscreen near the edges.

It does provide good drop protection. I used it for about 3 months and finally decided I didn't like it for the functional reasons I described.

I am now onto the next generation treo phone, so I am looking for a better solution too.