I'm not really sure what I should think of shared dreaming.
I'm rather open minded, so I do consider that it's possible, and I've read a few rather convincing arguments on these forums in favor of shared dreaming.
It remains one of these things noone can prove nor disprove.

Regardless of what I think of shared dreaming though, I dislike the idea that another person could enter my dreams, and have the power to shock me awake in the way I experienced.
If two people actively try to experience a shared dream together, it's a different story.