iOS 9 brought us an updated Notes app, one that provides a way to add a lot more than just text to a note. For those folks who still find it wanting in terms of features and capabilities, Google just released Google Keep for iOS, a free universal note-taking app that mirrors the Android version and that can be accessed on the Mac (see below) from any browser at http://keep.google.com.
The app lets you capture notes, add lists, take photos, and even take audio notes. Once captured, the notes are able to be edited or shared from any device. Notes are organized with labels and bright colors in a very "sticky note" type UI.
As with Apple's Reminders app, Keep provides a way for you to be reminded about a note at a specific time or place. Voice memos can be automatically transcribed with remarkable accuracy and speed.
Google Keep is free, it's powerful, and it's multi-platform.