Generally speaking, I liked the first episode. It certainly wasn't an hour of television that made me vow not to waste my time with the remainder of the series. There was a fair amount of classic Sorkin in there - quick dialogue, heavy doses of liberalism, although not much walk and talk yet. That won't be to everyone's tastes, but as someone who was a big fan of Sports Night and The West Wing, and who thought that Studio 60 was, by and large, pretty good, it doesn't bother me.
I agree with Redcap's comments about the dynamics though. The Jeff Daniels-Emily Mortimer relationship seems set to become a will-they-won't-they-oh-yes-they-probably-will affair throughout the season, which would be a bit of a shame. Then there's new guy/old producer/nice-but-ditzy blonde girl triangle. At some point you're expecting a network executive to become uncomfortable with the show and start ordering changes which will be resisted, and that tension will run for at least a few episodes. Then there'll likely be something personal for at least one of the characters to deal with. You'd like to think that the show won't descend into cliché and the unimaginative, and Sorkin's clearly clever and talented enough to manage this, but the danger is definitely there.
Anyway, I'm looking forward to seeing how it pans out. A tentative thumbs up from me for now.