Like any adult animated comedy it can be a real pick and mix bag. If you decide to marathon a show like this expect to notice significant shifts in both quality and themes between seasons. Of all the adult animated family sitcoms though, this is the one I have least often found boring, disgusting, or abhorrent. Let's not dance around the issue; those kinds of moments come with the genre. American Dad is the one I've seen get the most visible effort put into it, to the point it does have real changes in the status quo that span seasons sometimes, and (while silly) plotlines that can span over multiple episodes. It creates a bit of intrigue when they pop up, but you know it's pretty much all a massive joke anyways.
Tl;dr Last time I watched this show was about a year ago, and it still felt like it had people who cared about the show and characters working on it. When a show manages to get over 10 seasons and has that sort of dedication it's worth a look.