It's awesome for things involving communication and relationships (banking, purchasing, and so forth) and for accessing content (Youtube is my main music discovery service, for example).

But I don't like doing everything in a browser. All the things you mention are transactional, but when I'm (say) writing music I much prefer to be in a native environment because the transactional stuff is a much lower priority. It's distracting, for many tasks. At the very least, I want to run some things without a browser frame of tabs, URL bar and so on without necessarily doing so in full screen mode.