This looks inviting, but won't automatically installing an android app when you visit a webpage (with one tap) create a giant security hole, not to mention creating more clutter and consuming more space on your android device? This is more of a job for HTML & Javascript because these apps are temporary and then discarded. Why do we need Java for that?
This is a great way to have app, installs because it invites people to see the full app. Instant apps. is an isolated activity which can do a few tasks. Great for the physical web for example (controlling a machine). I think it is more confusing to mix HTML with an app.
My feeling says this will be a great success!
Google released this with a few partners and soon everyone can use it.