A critical reading of Poe's "The Tell-Tale Heart" differs from a plot summary in using the tools and techniques of literary criticism. As you complete such an assignment, you should begin by analyzing the narrative voice of the story. You should note that we see the story through the eyes of an unreliable first-person narrator and that as the narrator attempts to justify his claim that he is not mad, he inadvertently convinces us of his insanity. The unreliability of the narrator also makes us as readers speculate on the degree to which the old man was an innocent victim. You might also look at how the story fits the genre of "dramatic monologue."
Next, you might examine the implied audience or the "you" of the story and how the use of the second person draws the reader into the story.
Finally, you might look at how the very disjoint style of speech and tendency towards overemphasis and hyperbole helps construct the personality of the narrator for the reader.