Smartphones I do not like: the gPhone, the iPhone, virtually all BlackBerrys, and the vast majority of Windows Mobile-based handsets.
Smartphones I do like: the Handspring Treo 600 and 650, and their eight-year-old predecessor, the Visorphone:
The main reason I bought the Visorphone instead of the more functional Treo is that the Visorphone can be detached from the Visor handheld. That means I can still use the PDA / organizer functions where the phone isn't acceptable.
It didn't come with a battery, so I had to get creative with some tape, solder, and spare wire.
Underneath is the battery pack to my old Motorola v60i.
The phone runs on GSM 1900/900. The handheld that's running it is a Visor Deluxe with 8MB of memory and a 20MHz Dragonball m68k CPU. And since the Visor Deluxe uses RS232 instead of USB, it's one of few Palm-powered handhelds that will actually sync with the x64 editions of Windows.
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 6.0 x64; en-US; rv:1.9.0.3pre) Gecko/2008111500 Minefield/3.0.5pre
Laptop: HP Compaq nx6325 - Turion 64 X2 @ 2GHz, 2GB DDR2, 100GB HD, ATI Radeon X300, 15" LCD, Seven Pro
Handheld: Palm Treo 650 - Intel PXA270 @ 312MHz, 10MB RAM, 32MB flash, 2.7" LCD, Palm OS 5.4