I have compared Photo Stream and Google+ for this scenario (i.e. taking photo on iPhone and see them appear on the respective cloud storages). Despite Google+'s awesome anytime-anywhere availability, its upload/backup speed feels much slower compared to Photo Stream. But the fact that I need a garbage like iPhoto to access those photos on Mac makes it a deal-breaker for me.
So while I'm already sold on Loom's Mac-based access to the photos, I'd be willing to jump ship if the following are satisfied:
1. Upload/Backup should feel as instantaneous as Photo Stream, especially with WiFi connections.
2. (This is different than my original point) Loom shows commitment to its users by some kind of a promise that even if it gets acquired it will not shutdown the essential servers or at the very least not ask us to archive and download all the photos we've put into it so far. I had a lot of hope with Snapjoy and it turned into a killjoy after its Dropbox acquisition. I'd like to stick to a service like this on a long-term basis.