didn't let you make a selfie while looking at the screen. (no front-facing camera)To be fair no smartphone did in the first couple years.
didn't let you copy/paste text (for the first 2 years of iPhone)
I got the iphone right after this shipped just by chance, and I couldn't understand how anyone lived without it. Also the had just added the "task switcher" carousel and the precursor to the control center, both features I used heavily and was surprised to learn didn't exist just a few months prior.