Yes, it's great for all the reasons you said and more. But I wouldn't say it's a big win for user rights
yet. It might end up even more locked down by carriers and OEM's
because it's open source (and of course because Canonical will
allow that to happen to gain some market share):
http://www.theverge.com/2013/2/19/4005514/ubuntu-phones-2014...
Plus, don't forget all the deep Amazon integration, and who knows what else in the future, so they can monetize it. It might be that the whole OS will watch your behavior to target better content at you or something. I don't know how that will end up versus privacy there, so we'll see.
I hope Google implements Samsung dual-view idea in stock Android, though, as it would solve 90% of Android's "tablet app problem", as you can use two "phone apps" side by side, so scalability is not such a problem anymore as it looks like the app on a 6" or 7" device, which isn't too bad, and it also gives you the ability to use 2 apps at once, which should be better than just using one in most cases.