I'm not familiar with this space but is this the first of its kind? Or are there better ones? I actually think I may want to use it to manage my s3 assets. Would be helpful to know if there are alternatives and why this is better
There's quite a few programs like this, and I've tried them all. What makes this look promising is the peeps behind Cyberduck fame are creating it. I always wanted that feature in Cyberduck, where you can mount any arbitrary legacy file system. All the others I've tried are half-baked attempts and horribly buggy.
I am a happy customer of ExpanDrive (http://www.expandrive.com/) which is very similar, except that it is cross platform and looks like it support more back-ends.
ExpandDrive recently greatly enhanced their product by providing background uploads.
Cyberduck (and apparently Mtn. Duck, judging by the screenshots) is equally cross-platform; which is to say, runs on recent-ish versions of OSX and Windows. Expandrive looks decent, but for my purposes fuse is good enough, and free.