I use google docs/drive on my Macbook Pro, my Windows machines, and on my Galaxy Nexus. I also use it to collaborate between co-workers, clients, friends, families and loved ones.
Two really huge issues that I have with it though, both around usability.
First Google Spreadsheet on my Nexus is horrible. It is the most incomplete UI that I have ever seen Google release. Edit a row, but not really. It doesn't even have add column, or stretch columns to show content. Plus what good is a spreadsheet that I can do any calculations with. HORRIBLE. The part that really frustrates me is that even when I use Google Chrome on my Nexus, the UI defaults to a mobile version. WHY?
Second issue, is with Google drive. Why is it that Drive looses focus of what folder I am in when I create a new document. Everything is placed on the root, then I have to track it down then move it to folder that I want it to live in.
I love the idea of Google docs, and Google drive, I love the idea that my content can quickly be accessed on any device, but Google has a long way to go in usability.