I love Family Guy, though I'll concede it took me a bit to get into it, so I think that establishes a history of at least understanding Seth McFarlane's style, but holy cow was American Dad bad. It turns out Family Guy would really, really stink if it wasn't constantly jumping out to flashbacks.
But the bigger problem is the characters. One can't fairly criticize an opening show for shallow characters, the only antidote to that is time. But when three of the six main characters are first and foremost annoying, that's not a good sign. (I have a saying about character building, which I believe I've stated here before: One must be careful about creating an annoying character for a TV show or movie... you might succeed. Jar-Jar in the Star Wars prequels is probably the canonical example of this. This is one of the corollaries of one of my mottos, "Never engage in an endeavor where the worst-case scenario is complete success.")
The eponymous dad is too gung-ho, and serves too often as a glorified deus ex machina as he abuses CIA powers. The alien is annoying as heck with no apparent redeeming virtues, though one hopes some half-way decent side stories could emerge from that. Watching someone stuff themselves fat, and, ah, essentially defecate on the floor multiple times in one episode (not literally, but clearly the implication) just isn't my idea of fun. Apparently his species has mastered space travel, but not the toilet. The goldfish, which appears to be a main character, is even more annoying and doesn't even have the virtue of making interesting side stories possible; the story of his origin is most likely the only remotely interesting and plausible thing about him and they shot that wad in the opener. (Maybe he'll get shuffled off? Maybe he's just the first in a continuing series of side characters? I can't imagine the writers would so willingly jump into a painted corner like that...)
The other characters were uninteresting, primarily because they were underdeveloped, but as I said that's only correctable with time.
And the scenes involving dragging around a mostly-dead dog just made me cringe; that's not a good sign. I'm hardly "unshockable", but if you're making me cringe, you're probably not impressing most of your audience.
The mother's character reminds me of the mom in Family Guy, an apparently mild-mannered housewife who underneath that demeanor is surprisingly wild, and she might turn out interesting. The boy, whose primary job in this episode was to go mad with power, was so-so, probably just needs development, although asking his sister if she wants to do him, no matter what the context, in the first ten seconds of screen time just isn't the way to introduce an endearing character. (In fact, I hadn't really thought about it that way until I wrote it that way just now.) And the sister was just neutral, neither particularly developed nor particularly horrid; mostly I felt pity for the annoying world she lives in, and if she's got angst, I'd think it was fully justified.
(I can't help bet compare this to Family Guy, where none of the characters were actively annoying in the first episode, and while the two older children are both still a little underdeveloped, at least I don't cringe when any of them come on the screen, although if the older brother entirely disappeared it probably wouldn't hurt the show. You have to be careful when making a stupid character, it has the same "success" problem too.)
Just bad; if it somehow makes it into season 2 I may re-evaluate it. In the meantime, I've got better things to do with my rather meagre TV viewing time, Family Guy being one of them... unless it has lost its edge.
I remember when Scott Adams, the author of Dilbert, spread himself too thin with the cartoon and the TV show. I don't have a reference for the quality of the cartoon show without the cartoon, but during the run of the TV show, the quality of the cartoon really took a nose-dive. Most Dilbert daily cartoons before the TV show had effectively two punchlines in the final panel, something that once I noticed really made me respect him, given the constraints of the medium. Other cartoons certainly do it when they can, but Scott Adams pulled it off routinely after his first few years. As he worked on the TV show, the punchline count dropped to an average of one, and it was usually of a lower quality to boot. Now that he's back to just working on the strip, its quality has increased again, and Dilbert's primary problem in my mind is that it's in a bit of a rut; I liked it better when it wasn't 100% set in an office, but I'm willing to believe that I'm in the minority on that one. (One can imagine what the Dilbert TV show might have been if he hadn't had the cartoon, but I think that he most likely spent the majority of his creative effort on the TV show; I don't think it could have been much better. But it does provide an example of Dilbert stories that aren't 100% set in the office.)
I don't know how much Seth McFarlane is in Family Guy; sometimes the creative guy drives the whole show, sometimes he just sets up a good thing that can live on without him. But if it is the former, I hope that Family Guy doesn't suffer for the involvement in American Dad, or McFarlane may lose big by having two mediocre (and subsequently cancelled) shows, instead of one good one. (It's great that Family Guy came back and all, but it's still got to be somewhat on the bubble.)