Amazon S3 can work for photo backup, but it’s generally more of a storage backend than a polished end-user backup service. If you’re comfortable with a more technical setup, S3 is flexible and can be cost-effective, and Amazon has supported bulk ingest by shipping drives for upload.

The main caveat is that S3 is not a normal filesystem, so you typically need extra software to use it conveniently. From the answers here, common approaches include:

• s3fs: mounts an S3 bucket like a local drive via FUSE
• s3sync: syncs local folders to an S3 bucket
• Jungle Disk: a user-friendly option that uses S3 and encrypts files before upload

If you want a robust, simple backup workflow rather than a DIY solution, a service built on top of S3 may be a better fit than using raw S3 directly. That can give you easier uploads, organization, and backup management while still benefiting from S3 storage behind the scenes.

So: S3 is a solid backend, especially for technical users; for most photographers, an S3-based backup product is usually easier.