1. Google drive doesn't understand linkfiles, so if you want to sync your usual documents etc., folders on a Mac, you can't just link them into the Google drive folder
2. It is slow, and reports 'unsyncable' files, instead of resolving them quietly using the internal file id of the file; it seems to rely on hard path strings.
3. It maxes out the CPU when iterating the drive folder and or syncing
4. It seems to be slower
5. It doesn't show you enough info while it's busy about what it's doing.
6. It doesn't let you paste your password into the signup screen. I have a LONG password.
7. It doesn't let you report problems except via Google Groups, which is a bit like going into a busy market place, grafittiing on one of the flagstones, and hoping that the emperor in the palace above you can read your comments. There's no accountability with Google - for anything on their platform. Their stuff doesn't work properly, except for the search engine, and you cannot trace anyone down to hold them accountable or ask them to fix it.
Dropbox has none of these flaws.
In Dropbox, if you want to, for example, backup your desktop folder, and your documents, and pictures folder, and your system preferences and mail, you just do this in the Terminal:
ln -s /Users/`whoami`/Documents/ /Users/`whoami`/Dropbox/Documents
ln -s /Users/`whoami`/Desktop/ /Users/`whoami`/Dropbox/Desktop
ln -s /Users/`whoami`/Pictures/ /Users/`whoami`/Dropbox/Pictures
ln -s /Users/`whoami`/Library/ /Users/`whoami`/Dropbox/Library