Deep is your typical horror/thriller story.

Like any good thriller story it hooks you up with it's mystery. Why missing people returned? What happened to them? What will happen next? Author uses suspension quite skillful to slowly bit by bit uncover those mysteries. Art is also good at creating sense of unsettling unease and that is exactly we want out of such stories.

Overall it is good manhwa for fans of thriller stories, all others will have a bit of trouble trying to enjoy it. Do not expect something special or outstanding out of it and just relax and enjoy. Personal suggestion: some atmospheric music in the background definitely increases immersion and enjoyment of any manga, my choices are post metal bands "We Lost The Sea" and "The End Of The Ocean".