I recently had to write a one-page letter on my iPhone and email it to somebody to print out, sign and hand to a third-party. It wasn't by choice, it was just an urgent request and I had nothing else with me.
Surprisingly, it wasn't nearly as painful as I expected. It didn't take me long to write the letter (the default templates helped a lot), making edits was fairly easy and I had no trouble being able to read over what I had written.
So for small edits to existing files and quick docs it's usable, though clearly not as good an experience as using the same suite on an iPad.