As described in this thread, the new version of dropbox backup is great but has a major downside: files stored via backups can no longer be accessed within the dropbox app!
Quoting @mbriney from the above-linked thread because I can't say it any better:
I understand the principle of having the major "backups" be in a different segment of dropbox.. but it shouldn't be that hard to access all the files. Maybe inside the regular current Dropbox app, feature a button that allows up to actually open the files that are in this "backups" section? OR maybe create another "Dropbox Backups" app that will allow us to remotely view these backup files without having to go thru the browser?