So, that ending (spoilers)
What would make the "it was all in his imagination" ending kind of interesting is, if there are some clues about why he attempted suicide.
In the beginning, glimpses show that his dad was a jerk and subsequently his childhood was moderately unpleasant.
Guilt from the Kojak/Callahan tunnel incident? He kept seeing that hooded figure throughout.
I wanted to like the ending more.