Say you were a regular Fringe watcher at some point during the past, but you've dropped off in the past year in the face of one contrived plot twist too many. In that case, tonight's episode would be an excellent place to jump back on. Without going into spoilers, tonight's episode feels like old-school Fringe, in all the important ways:
1) Walter is getting out of the lab, and we're reminded that half the fun of Walter Bishop is seeing him interact with his environment.
2) There's a creepy mystery, and things just get scarier and weirder as the episode goes on — there's no "creepy stuff that sort of peters out once we know what's happening" this time around.
3) It's very much focused on our main trio, and their relationships advance in meaningful, fascinating ways.
4) You get some huge hints about what's going on with the season's arc, and the big mysteries have a promising new twist.
All in all, I'd say this is a pretty decent episode for people who miss the "old" Fringe.