I can understand how fans of filmmaker Roman Polanski could love this movie- and I could understand how some could totally hate it (Ebert was one of the few who couldn't understand why people weren't running out of the theater). After a first viewing, I'm not sure I could fall into either category, however as someone who can't get enough of Kafka and bizarre dark comedies of paranoia The Tenant is effective enough for its running time. Or maybe not- this is one of those cases where it might have been more of a masterwork if it were a half-hour Twilight Zone episode, with Serling delivering the coda as Terkovsky (or whomever it might be(?)) writhes in his bed in bandages. It's very similar in the treatment of the doomed protagonist as Repulsion was, however it could be argued that there was more ambiguity, more of a sense of the surreal coming out through a sustained disintegration of character and location (and, quite frankly, a better lead performance) than the Tenant.
As it stands, The Tenant does have an intriguing premise, the kind that one doesn't tire telling about to other people: Polanski is a Polish émigré to Paris who takes an apartment that was most recently acquired by Simone Choule, who jumped to her near death out of the window and died soon after. But the other tenants are conservative to the max in terms of noise; after a Saturday night at Terkovsky's with a few friends, there are complaints of too much noise. It won't happen again, Polanski's good-natured but slightly nervous tenant says, but there is no peace even in moving a cabinet or a chair. Soon complaints get registered against another tenant, but from him? Can he register complaints? This is a case of not so much mistaken identity but of there being a lack of peace of mind with oneself and the surrounding people. As the downward spiral goes on, Polanski ratchets up tension (and, dare I say, black-comedic laughs) by showing Terkovsky in the midst of a horrible dream- one of Polanski's strongest scenes from the period- and in finding teeth in the wall, not to mention the bathroom across the way (which, I might add, is always a cinematic lynch-pin of horror and surreal madness).
But somehow, the film never really feels all that significant aside from its excessive design as a would-be mind-f*** machine, with Terkovsky's tenants only seeming to not be what they seem for a little while: there's not as much suspense when finding out that they really aren't out to get him, which makes the paranoia more self-fulfilling. At least once or twice I thought to myself as well 'why did Polanski take the title role for himself?' It's not that he's at all a bad actor, and he has appeared in several films and plays that aren't of his own direction. But aside from being great at looking awkward and tense, like in the church, or in his moments of sort of flipping out when thinking that they really are out to get him to kill himself, his transformation is less creepy than tongue-in-cheek, a test of himself to see if he can pull it off, which he doesn't entirely do. Despite Polanski working at it well to look like the meek and frazzled Terkovsky, I could see at least a few other actors who could pull it off with more subtlety and affecting personality. By the time one sees him in drag, it goes between cringe-worthy and true camp, particularly when he goes for the double-climax at the end (which, of course, is of little surprise).
And yet there is pleasure for the film-buff and Polanski fan to see the supporting cast try and dig into the much more ambiguous characters (Winters and Douglas do this the best, even as they have to strain through limited characters), and the unexpected moments like Polanski and Adjani getting hot and heavy during a Bruce Lee movie, or when he gets really drunk, or in one almost random scene where he slaps a kid near a fountain, are rather brilliant in and of themselves. It's a very good film, and one that could maybe stick my attention up when on too many coffees after midnight. But an essential film? Not exactly.

I find it rather useless to comment on this "movie" for the simplest reason that it has nothing to comment upon.It's similar to a rotten egg which has nothing good to show to the world excerpt for the fact that it is rotten as other endless number of eggs have been before it. But since a comment is mandatory for such a grandiose insignificance ...
Filth is definitely the proper word to describe this movie created in the same manner as any other Romanian "movie" directed by Lucian Pintilie who insists to depict the so called "Romanian reality" following the Communist era (1990 to present days).
Under no circumstances recommended for people outside Romania as for the others (who lately find amateurish camera, lack of plot, lack of directorial / actors's quality etc, noise etc. as being trendy and even art-like) : watch & enjoy this "movie" (as I know you will) but do the other well intentioned IMDb members a favor, don't write an online review for it will misguide, irritate and in the end waste their time.
On the other hand this movie (among others) has some value whatsoever, an educational one for it sets the example for : "How NOT to make a movie."