A few edits would have helped tremendously. SPOILERS

Imply that Joe, the elevator guy and the lawyer are not real at the end of the film - deleting about three or four shots can accomplish that.

Don't give away so much of the plot, so soon. A reveal of a crazily-rigged apartment at the very end, would have been really effective.

Get rid of unnecessary and confusing "details"....scratched bed frame? Brown water? The buzzer ringing at the end? The cat and the exterminator? Let the camera card reveal a bit more to the kid in the final shot. Quicks shots showing Danny himself leaving to buy groceries (I know - the battery issue, and placement).

I think Danny had been living there, killed his grandmother, killed the girl, killed the exterminator and killed the cat. I don't buy "sleepwalking." He imagined Joe, the elevator guy and the lawyer. The building was trying to evict him. He was psychotic. However, you do have a neighbor implying that he's only recently arrived (the gay(?) guy in the hall). Maybe get rid of those scenes with the neighbors. I dunno. The lawyer could work as a real person, of course...it would provide a bit of a wrap up needed for the eviction plot.

Yadda, yadda. Yep, this is a "poor man's Polanski." Ambiguity in the wrong hands is just annoying. I think that making this particular film more "literal" would have helped. The guy's crazy, but we don't get the "pay-off" till the end. I do think that he killed himself when he finally realized that he'd lost his mind. (But I don't think that he created the hinged/nailed door originally for suicide.)

It was ODD seeing this film on the day of the Colorado theater murders, and knowing of that killer's rigged-apartment.

I DID like the set dressing/design - good location and set (I doubt that the apartment was "practical," but it could have been).