It seems more camp or tongue-in-cheek than ST but still ventures into serious territory. * POSSIBLE SPOILERS IF EPs NOT SEEN YET * Teaching Isaac about practical jokes was interesting altho their Continuity Person was asleep at the switch. The leg that fell out of the ceiling was complete while, when the victim hopped onto the bridge, it was only missing below the knee. To me, it feels more light hearted and upbeat. I thought the exploration of relationships represented by the Doctor and Isaac was interesting. The final scene when Isaac makes it rain on the bridge was hilarious, had me ROTFLMAO. The expression of the rest on the bridge was exquisite.
The light at the end of the tunnel is a large round brilliantly lighted room with a tunnel exit across the room where 8 tawny heads slowly swivel as a pride of hungry lions watch you enter the room.