I think Gmail is great but I agree with this author that the old text labels for the buttons are preferable and more user-friendly (at least for me) so I switched back.
I think the Dropbox ability to drag and drop files is an improvement but it hasn't made that much difference for me yet. And as valuable as Dropbox has been for me, I admit that I am still waiting to see exactly what Google Drive will be.
Make Gmail and Dropbox Easier to Use | PCWorld
If you don't have Dropbox yet, go here to get it and both of us will get 500 MB bonus free storage space.