It all sounds fine and nice - but in my view when you boil it down - it's just a web server. Sure it's a web server that is automatically set up and accessible via the browser - but it's still a web server.

I see no mention of it as a distributed or P2P type service in any of Opera's developer specs , which means that whatever it is you're hosting is hosted locally and using local bandwidth. For small items, that's fine but in the new era of metered bandwidth, I think users with large media/photo collections would be wise to think twice before hosting content on their own.

Another reason why local servers (unless I'm missing something) are somewhat troublesome, is the fact that they are only accessible when the local server is physically on. Sure - your photos and media don't have to be available 24/7 but that's something that a web based service can offer.

For me, I've run web servers for far too many years dealing with the seemingly infinite security, bandwidth and availability issues that need to be considered to really give Unite a chance on my desktop browser. Does Unite offer the IPS/Firewall controls that will enable me to actually be secure? Does Unite open up my network to additional risk?

Yeaah I'm a little pessimistic here, but those criticisms aside - Opera is taking the anti-cloud approach here and it is somewhat refreshing. Not everything should live in the cloud. Some things do work better locally and for some users Unite will be a valuable service. Setting up your own web server is not easy and not everyone wants to use Facebook to share all their stuff.

Now as to whether or not other browser vendors will follow Opera on this only time will tell.