Those are the two biggest differences, for sure.

All the big players have done a good job of speech to text (at least for USA English—saw an Englishman have to break into his best John Wayne impression for an on-stage demonstration about a month ago). But the Echo hardware does a great job of isolating your voice and the platform allows us to write skills for it quite easily.

I wouldn't be surprised to see the other guys make steps in a similar direction if the Echo continues to succeed.