I use Google Docs daily from both my iPhone & iPad. It's very easy with a newly updated (just a few days ago) App that works on both iPhone & iPad. Made by Google it's simply called "Google Search".
A bit of a misnomer, as it's a full featured brilliantly simple & attractive. It has a button for Google Apps. That takes you to docs, calendar, tasks, reader, etc.
I'm so pleased with this app I use it constantly. Youll love it. Just go to the app store & grab it for free.
Google doubles the usefulness of iPhones & iPads, they have truly brilliant, well designed apps.