It is an enjoyable film...but one with several natural endings. And that kind of makes for a fail. You're ready for the movie to be over after it concludes and then you wait until it concludes again, and then you wait until is actually concludes.
However, it is tense, which is a De Palma hallmark, he knows how to make for a tense thriller, and that is where the appeal is, that is what really sets Dressed to Kill above a lot of other films. It plays on the nerves.