Evernote has been my preferred note taking app for a while now. It allows you to write, and more importantly, access your notes, on any of your devices.
Is it perfect? No. It kind of holds your content "hostage" in that you can only view your notes from the app or on the web-based version. However, for me, the convenience outweighs this drawback.
Notes are saved in notebooks, which is especially useful for work purposes. I have different Notebooks for each project I'm working on. There are some other neat features like the ability to record audio and attach them to notes - something that has come in handy in meetings. You can also save actual webpages to a notebook in Evernote (I personally don't use this feature).
Anyhow, if you're looking for a good cloud-based note taking app, try this one out. As a simple alternative, Plain Text is a basic note taking app that synchs with Dropbox.
Let me know if there's another one you prefer.
Visit evernote.com or get the app here.