Apple's iPhone essentially reinvented handhelds from crude, proprietary systems to a sophisticated platform that made much of the desktop experience work in a handheld context. And it's a cool device, to boot.
Pros: Native Exchange e-mail and calendar (third-party Lotus Notes client available); intuitive gesture-based touch interface; VPN; strong HTML support; Wi-Fi support; built-in RSS reader; iTunes sync.
Cons: Requires iTunes to sync data; no cut and paste; only one app can run at a time; proprietary development system; proprietary apps distribution; poor security features; latest OS is sluggish and less stable.