Backups can be scheduled making for an unobtrusive experience as they can be set to run when you are not using the PC.

Data is locally encrypted before uploading to Spideroak. They cannot recover your data even if they wanted to since it is stored in encrypted state on their servers.

Thus you have a single service for all of the things instead of having to use multiple clients or services.

SpiderOak updates only that part of the file that has changed, saving bandwidth and time.