5 from me. I just didn't enjoy it. Probably had something to do with the Olivia focus (not the next episode though - WOO!), and a lot to do with the stupid characterisation of Peter in this episode that I still can't wrap my head around. No character growth from either of them, it seems, and I was bored.
Would have been a six but I still can't sort out my feelings towards that terrifying/hilarious dancing corpse scene that I know I'll be dreaming about tonight. Thank you Fringe!