Loved it.  I'm only disappointed in the ending.  I know that the intruders are not real and I wish they actually were.  "You were right to be worried."  That would've been a better ending, a subversion, and still tied into the theme.  In my opinion, at least.  Even better if the "good" ending still had someone breaking in too.

The ambiguity of the ending can be argued what is real and what isn't but the theme sullies that ambiguity.  There's no real weight to your supposed death because of it.