Well, since you haven't seen any new episodes, it'd be hard for you to identify what I'm talking about, but here goes...
My biggest problem with the new FGs is that the episode plots have taken a back seat to the gags. With the older classic episodes you had a good flowing plot with gags mixed in that, while seemingly distracting, were so funny that they did add to the episode as a whole. The first two episodes from this season (Passion 2 and Chris' teacher) were very good episodes in the same vain of classic older FG. However, after that, it either seemed like the episodes had non-sequitir plots, a la recent Simpsons, or just a string of gags with no real plot at all. And a lot of the gags aren't even that great anymore... it seems like he's just adding in nostalgic stuff like He-Man and Star Wars just for the sake of it, although a lot of people here seem to be eating it up. "OMG it's He Man d00d!" or "OMG he dubbed in the audio from the end of Star Wars!" and the like, as if a ten second gag made the entire episode good. If I wanted to see a string of gags and laugh maybe twice in a half-hour while sitting stone faced the rest of the time, I'd watch any episode of The Simpsons from the last five years.
By contrast, I've come to love American Dad, but it's nowhere near as popular among the MacFarlane fanboys here.