To start, the app prompts you to create a file (which is essentially a blank document) or a new folder to hold multiple files. Once you've started a document, you're presented with a simple blank page. Well, perhaps the page is not so simple; it looks like a crinkly white sheet of paper that's been run through a typewriter a couple of times without being written upon. Users can choose from a dozen or so different themes if this default isn't to their liking.
The on-screen keyboard is similar to the one you usually see on your iPad, but with an extra row for numbers. A keyboard icon at the end of that row offers quick access to other commands. (This function is available only on the iPad; the iPhone version of the app offers only the basic iOS onscreen keyboard.)
If you turn on the app's autosync feature, you can use Write 2 HD on multiple devices. This requires linking your Dropbox account to the app; once you've done that, you can start a document on your iPhone and continue writing on your iPad, or vice versa. It's a handy feature for users who might want to take notes while in transit, and then flesh their thoughts out later on a device better suited to long-form writing.
While writing, you can turn on the app's autotext and text expander features to help churn out copy at high speeds; once complete, you have the option to send the document via email or save to Dropbox as a text file, print it, or save it as a PDF. This is mostly pretty standard stuff that you'll find on many composition apps, however.
Where Write 2 HD sets itself apart is in two features. One is security: Users can activate PIN-encoded security, making sure no one else can see their notes and documents without permission.