By the way, recently I started to use BTsync to get back control (I would prefer an open-source implementation, but hey) and it feel so much better. Sample workflow: take picture with DSLR, import them on desktop at work, near-instantly get them synched to my phone, check and remove bad shots on my phone, also rotate and adjust them, have the edited and filtered pics ready on my laptop back at home, have all the thing on a linode where I have some scripts doing renaming and analysing. And, guess what, all of this in China, where dropbox and google drive are often unreachable.
The most important in this workflow, which I also use for music, is that when I remove a picture or a track, I want it removed from all the devices, and never come back before my face. It is suprisingly difficult... (In both senses: it is artistically difficult and necessary to decide to delete for good a file, and it seems technically impossible with services like Google photo, Dropbox's camera upload, etc.)
On thing i noted as beeing polisheble was how the conflicting was done and renames of files.
When a file was renamed the other browsers acted as if the file had been deleted then recreated.
Disclaimer: I contributed some parts to the project.
What do I miss?