I can't understand how people trust (or even care about) server-provided encryption. There's no guarantee they or their friends can't open it on their servers. Unless you use your own solution, their encryption only provides protection in transit, against unaffiliated third parties.
Link encryption is good, and it's helpful to ensure the only attack vector is the service provider itself, not sub-contractors or someone being stupid and throwing away drives.
That said, Dropbox has done a pretty good job of lying about how much security they offered users in the past. But someone providing a service like this with a reasonable security policy which is openly communicated to the users is still better than no security policy.
When it comes to zero-knowledge encryption, it is hard to know how their implementation holds up without external audits. This is the same for other encryption applications (google Truecrypt audit).
If you have enough devices yourself does it matter much? I'd take uptime over redundancy. I always have 2 work pc copies + 2 laptops going. As long as they don't sync empty folders back down I don't mind a services that's only got light redundancy.
Seems to be owned and run by OVH France.
But without encryption and private keys, i'd rather rent a server and use Duplicati.