Starting with the basic things that everyone who invested in smartphones at the time wanted, i.e. email, going through hilariously high cost (the reason behind it known only to insiders - Apple was in full rent-seeking mode, and required a portion of your phone bill as payment for being able to use iPhone. Not joking, that's why there were special iPhone-only tarriffs), it lacked physical keyboard, copy&paste, and a bunch of other things. iPhone 2G was also slower at running iOS 1.0 "applications" than higher end Nokia symbian phones (that used the same webkit core in browser).
Symbian devices were well known, and were more commonly considered "smartphones", as "palmphones" generally only got interest from people who really needed the power (a bit of chicken&egg issue).