Other than pure fingers crossed hope that it does something cool, where does any excitement stem from? Contextual awareness? Dynamic content delivered as you need it? Bixby launch announcement echo'd Google Now in 2014. What bothers me personally is that always on display, facial recognition and other features that Samsung has implemented ARE actually cool and usable. Their development efforts should be on this level, not targeting Google head on.
I anticipate that the big gotcha that is still mostly hiding is that Bixby is going to require a user to utilize Samsung's native email, calendar, contact apps, etc. This is far and away the most reasonable and probable way for it to access email, calendar etc which is mandatory to perform its functionality. If this is in fact true, it seems to indicate that there will be a lot happening on a device level that Google and Apple have the luxury of performing in the cloud w/o any reliance on the endpoint itself.