I think scopes are a really good approach to things, but I’m still working out in my head how to articulate it. So, bear with me here and don’t take this as my final explanation.
To me, scopes are the main way you’ll use your Ubuntu phone, not apps. And they’re important for two reasons (I’m making up vocabulary here): immediacy and aggregation.
Immediacy means that the information is right there at your fingertips. The Dash is the “main thing” on the phone, in the same way that the homescreen is on iOS or Android and the desktop and panel are on desktop OSes. Scopes let you build things directly into that home screen, in a similar way to how homescreen widgets do on Android, or extensions do in Chrome (and Chrome OS), or panel applets do in Gnome. But they’re a more powerful alternative; extensions in Chrome only get one little button to play with, and Metro tiles only get a small area which means they can basically show off one bit of information. A scope is interactive – it’s a lightweight app, essentially, with all the power of an app but the UI is integrated into Ubuntu itself. So you don’t have to go find its icon in your grid of icons and then tap on it and wait for it to launch; it’s always there. And because the UI is part of Ubuntu rather than being something separate, there’s consistency; once you know how to use the Dash, you know how to use any of the scopes, and any app developer can write a scope to put data from anywhere into Ubuntu.
Aggregation is what, in my mind, potentially makes scopes more interesting than just being apps with constrained UI. Any scope can call on and use the results from any other. So what this means is that if you’ve got a scope for RecipePuppy and another for BigOven, there can be a “recipes” scope which combines the stuff from both. So the recipes you want aren’t locked up behind the grid of app icons; it’s all pulled together. A “music” scope can show and play songs from Google Music, Grooveshark, YouTube, Spotify, a local folder of mp3s, all in one place. A search for music searches them all. But each one is its own individual scope, so if you only really care about Google Music then you can just add that directly to the Dash as a “top level” scope and it’s there for you. A “readable sci-fi books” scope might pull the “sci-fi” category of books from Open Library, Project Gutenberg, your own collection of books in Beru, your web server. So you can decide on the stuff you care about and make sure it’s all at your fingertips, and leave out the rest.
I should note that the above description is how, as I understand it, it is planned to work, and it might not all totally be in place yet; in particular, I think how scopes are aggregated is up to the scopes and you can’t just configure one yourself without writing some code.
I like this overall plan firstly because it gets to the heart of what I actually do with the phone – I can make myself a “social media” scope which contains twitter and G+ and reddit, if I want – and secondly because it’s not just a rip-off of the original iOS concept like so many other things are – I admire Windows Phone for the same reason. It feels more like all the stuff I care about is spread out in front of me – going back to a world based on separate apps feels like each thing I want to do is in a separate room, so I have to back out of the room I’m in and go into a different one. Having everything separate and siloed feels clunky, in a way I didn’t realise until I saw the alternative. There’ll still be apps, and (hopefully!) lots of them, but an Ubuntu phone is not just a box on which one puts a bunch of separate apps; it’s an information stream and the apps just support that. It’s like the idea of a lifestream from somebody, or why newspapers have front pages, or, I dunno. As I say, I’m still working out how to articulate this. But to me the Dash feels like the summary and contents page for everything I want, and I didn’t know I needed that summary… until I had it.