Spirit Visage says it increases regeneration and healing by 30% or something like that. However buying it, it doesn't seem like it increases regeneration any, even watching the energy regen ticks as Shen. Does it work, and does it work for Shen's energy?

I don't believe it works for shen's energy but that would be badass. Yes it does work just ask Mundo when he uses his Ult it restores so much HP he is pretty much impossible to kill.

It increases health regeneration (not energy).
Open your character tab (C) buy the item and see the health regeneration per 5 getting a bigger number.

Spirit Visage definitely works, it works so well it's getting nerfed in the next patch. I don't think there's any doubt the 30% healing/regen is working as intended.

It works, but is only worth it if you're playing a hero with mad HP regen (mundo), a healer, or a team with lots of heals.

It works, its a great item, though I always wished it could be upgraded to something for those odd long games.
Anyway, as someone already said, its getting a small nerf next patch.