In the key demo, yes. Overall viewership is down about 40%.
It's still too early to answer the question why but my guess is that people tuned in expecting Galaxy Quest (or at least, pew pew) and they're just not interested in the more serious/talky storylines.
We'll see if the trend continues as word of mouth about what it really is spreads. It could very well pull in the demo that may have been shying away before because of it being Seth.