1.7 is classic AoS rating, until the DvR numbers roll in.
I wager it adjusts up.
DVR ratings are really only useful for PR purposes. People who have DVRs almost always skip commercials, so advertisers won't pay much more for a commercial on a show with great DVR ratings. ABC doesn't really benefit from people viewing the show on DVR, except for the general increased awareness and exposure it brings.
But because Disney owns Marvel, Marvel Studios, and ABC other alternative media outlets DO help the show's cause. Disney gets the money from Hulu, Amazon, iTunes, Google Play, Netflix, OnDemand, DVD, Blu Ray sales, syndication, etc. That all works heavily in the favor of shows that are owned by the same parent company as the network they air on (including SHIELD, Agent Carter, Flash, Arrow, and iZombie but not the case for stuff like Gotham, Constantine, or Supergirl).
The season premiere is almost always the highest rated episode of a season. It was true for SHIELD seasons 1 and 2, which means 1.7 could very well be the high water mark for the show this year. Last season it started with a 2.0 and by week 5 it was down to a 1.56, and by the end a 1.30.
If this show had happened to land on NBC or CBS these numbers would be very, very concerning. As it stands now it doesn't really matter what the ratings are because fo the factors mentioned already.