The NYT review from the time of the film's release says,
Trelkovsky, the hero of Mr. Polanski's striking new horror film, "The Tenant," is a character who might have been invented by an Edgar Allan Poe who'd had the opportunity to read about Raskolnikov and Josef K. He's a particularly Eastern European kind of late 19th-century outsider set down in contemporary Paris. He is also—by the end of the movie—something of a joke, but an entirely intentional one."The Tenant," which opened yesterday at Loews Tower East, is the most successful and most consistently authentic Polanski film in yearsThe Film Connoisseur says,
After watching Polanski's Repulsion (1965), Rosemary’s Baby (1968), and now The Tenant, I can see why they call these three films Polanski’s "Apartment Trilogy". ... these three films are three very solid Polanski’s films, anyone out there who hasnt seen either of these should make it a top priority!
There is an inexorable feel to the film as Polanski, in the same way that he placed us inside Catherine Deneuve’s mind in Repulsion, takes us along with Trelkovsky as his entire identity is seemingly subsumedSlant Magazine calls it "One of Polanski’s greater efforts". DVD Talk says, "The reason The Tenant is so difficult a film, is probably that Trelkovsky is such an unpleasant person." Time Out has a negative review. Empire Online says, "The final reel ... is among the most despairing in the cinema, and acutely painful to watch."
HorrorNews.net has a review that includes this: "Rather than just simple paranoia, it is the overwhelming sense of persecution because he doesn’t belong". Rotten Tomatoes critics have a consensus rating of 90%. Roger Ebert despised it.