Mobile browers are awful. The Treo isn't bad, and it's the best of the above three, but the Samsung and Blackberrry browsers should be outlawed. They are that bad. They are so bad that Blackberry users' opinions about mobile services, mobile startups, etc. should be summarily dismissed.
iPhone: Browser is reputedly very good.
Touch screens rule. Once you've gone touch you'll never go back. Treo has it, Blackberry doesn't, and it drives me nuts. Trying to use a thumb wheel to touch a specific screen element is like dancing about architecture. It's briefly mildly entertaining, but ultimately stupid.
iPhone: Touchscreen. 'Nuff said.
Big screens rule. The Samsung screen is teensy and irritating. The Blackberry and Treo screens are bigger and better, but I want more. I hate having online real estate so crunched. It feels so ... 640x480.
iPhone: Big, bright mofo screen.
Mobile fonts are shit. The Samsung and Blackberry have fonts that only an MS-DOS fan could love. They are clunky, brain-battering and largely unreadable. The Treo fonts are marginally better, but they're still woeful.
iPhone: Lovely fonts, at least in pictures. Would design-obsessed SteveJ ever have it otherwise?
Mobile interfaces are thoughtless. The bizarro combination of escape key and menu key on the Blackberry -- neither of which are labeled in a way that gives any indication what they do -- is maddening. Controls are highly modal, which means something that works one way in one app works totally differently in another. A little thoughtful UI design would transform the market in a heartbeat.
iPhone: You can accuse Apple of many things, but thoughtless interfaces aren't one of them.