What does Google Drive do well? The system works and without the necessity of building complex folder structures. Because Google's search prowess is unrivaled, I usually need to enter a word or phrase to find what I'm looking for. There is also an ability to "star" files to assign a higher priority, sort only those shared to you, or review your most recent files. Unlike sprawling company or network drives that we've all used in the past, Google Drive gets the job done. I'm especially thrilled by the increasing levels of compatibility between Google Apps and Microsoft Office Apps. I haven't had to buy MS Office for several years as a result, and that's a huge savings.
What does Google Drive not do well? I am not a fan of email and drive partitions counting to the same storage budget. I would love to split those two from each other. It's also easy to use Google Drive as the digital equivalent of a kitchen junk drawer and store all sorts of files there.
What do you wish you had known about Google Drive before using? I should have known that Google would rely on its own search software instead of tagging and categorization, but it was still a surprise to see how unorganized the space could be if you didn't impose your own system.
Have you used a competitor to Google Drive? If so, how does it compare? I also use and pay for Dropbox for other reasons. Dropbox's performance hit on my computer makes me crazy, and I suspect I will soon be canceling it.