Roman Polanski is seemingly effortless in building a tense atmosphere of paranoia. The cinematography is duly vertigo-inducing and the music, I'm sure, will be nostalgic to me one day.
The only truly overt criticism I have is of the acting. Since I loved every other aspect of the film, it's a shame that the protagonist (played by Polanski himself) is so wooden in his performance. It's not necessarily bad, but it is generally lacking. It is not a major flaw however, and this film is still widely entertaining.
I look forward to seeing the other two parts of the Apartment trilogy in due time.
This film comes definitely recommended by me.