Well, sure, you can write your to do list in "Notes".
And then when you add something else, and adding it changes the priority or sequence order of the list, you have to backspace out your items one character at a time, and retype each line in its new position, since there's no copy & paste.
Ah, but you say, well, that's alright, I'll just type it out on "Notes" on my new $3500 Mac computer that makes everything simple and easy, and sync it over to the phone, so I can just grab it on my way out the door to go run errands. Can't. "Notes" doesn't sync between your phone & computer.
...
After six months, the iPhones only practical use seems to be, well, a fairly expensive cellphone & (text & jpeg only) email & web browser (albeit a crashy one). I still have to carry around an eight year old PDA for a To-Do list, a clear calendar, voice recorder, and a fully-capable web-browser & email client, but I hardly mind anymore, since the old PDA also lets me save files off the web & email, plus open & edit notes & spreadsheets, save them, email multiple files, cut, copy & paste text, graphics, and files, AND lets me transfer work files from home & work, just by plugging it into a USB drive or pulling the CF or SD cards out & popping them in a reader. & hey, it even has a nice big brightly colored touchscreen and comes with a second, high-capacity battery than you can switch out so you never have to wait for it to recharge. 8 years old, and it does 95% of all the stuff the iPhone should do, with a tap of the finger, & hasn't crashed in years. With a cell-service CF card, it'd be a phone as well.
The iphone platform has all the potential in the world to be the greatest handheld device ever made. Potential. Right now, it feels more like a waste of money.