Been using dropbox for a while for saving arduino sketches across multiple computers. There are no real gotchas and I also use it to share code with others.
I did use Google Drive but I'd have issues with it. Sometimes it doesn't always sync all the files for me. It's a shame because my Google Drive is much larger than my dropbox.
I am sticking with dropbox because it seems to always work. If Google drive was as robust I would probably move over to it.