For the record, it is definitely possible to only sync the files you want to on your phone - it's what I do. And as an anecdotal data point (FWIW), I've been using it since the Dropbox debacle, with a pretty large data set on weak machines and it's been solid.
Having said that, I completely agree with the open source thing, and am waiting for a good enough OSS one to jump ship.
But for anyone wanting to leave Dropbox, I can say at least my experience was a pleasant one (it's really nice to not have to worry about usage limits, or war criminals).
This must be something newer then because as early as a month ago I could find no way to do this. That may be failing of their documentation however I clicked every button/icon there was in the mobile app and found no way to do it. I can see now that by clicking the icon to the right of the folder name I can choose to have it "Auto-sync" which I assume means the data is stored on my phone but it's still confusing.
He doesn't want to selectively sync only certain files with his phone. He wants to browse the available files and then on demand download that file. This is a common use case for me also and something that dropbox supports pretty well.
Having said that, I completely agree with the open source thing, and am waiting for a good enough OSS one to jump ship.
But for anyone wanting to leave Dropbox, I can say at least my experience was a pleasant one (it's really nice to not have to worry about usage limits, or war criminals).