Just don't get disappointed when you try to assert your thinking onto the database - and it doesn't agree!
I have an indexed view right now where a complex query (which does not mention the view by name) was able to figure out that a nonclustered index on the view would work perfectly - I was impressed.
But a second nonclustered index on the same view couldn't be triggered without NOEXPAND even though I only queried and SELECT-ed a single column from the view AND mentioned the view by name!
So yes it can work in some very impressive ways - but can also fail in some super simple ways.
I read somewhere that sometimes it 'doesn't even bother to check if the indexed view is more efficient' if it determines that expanding can be good enough!