Overall, I was quite pleased with the iPhone's performance as a limited stand-in for my laptop, even though I needed an external battery to get through the day. Still, while I've said in the past that I could leave my laptop at home if the iPhone let me use a portable Bluetooth keyboard for text entry, I'm adding some caveats to that statement after last week's experiment.

The iPhone certainly performed yeoman service, lightening my load and providing most of the vital functions I needed while walking the show floor. But I also found myself frustrated by the things it couldn't do, and I had to revert to my laptop for "real" work in the evenings. While these shortcomings may be acceptable during casual use--after all, the iPhone is still a phone--they point to things Apple needs to improve to make the iPhone a more-viable business and power-user tool. They also highlight areas Apple will need to focus on if the company is to take the next logical step and make a larger, iPhone-OS device that can actually replace a laptop for many people.