The return of Scully here is expanded by a more integral role for her in this episode, where she actually experiences the unexplained, and has to wrap her head around it rather than have Mulder spelling it out for her. It was nice for a change to again have Scully being an active participant in the believing side of the episode, and not just constantly debunking Mulder's theories. This really did have a One Flew Over the Cuckoo's Nest feel to it, which was apparently what the writers wanted.
The ending may not be the cleanest or cleverest but it was still a fun episode to watch. 4/5