I'm encouraged and happy to see such enthusiastic reviews of this film, and from people who (apparently) never saw the play upon which it is based. Because that means that, for some, what the play had translates to the screen.
For me ... I saw THIEVES on Broadway. It had a stellar supporting cast and two of the same leads as the film: Marlo Thomas and, as her father, Irwin Corey. Marlo's husband was played by the late, great Richard Mulligan. At the time, Charles Grodin was director (having taken over out of town, when a bewildered Michael Bennett decided it was unfixable). In the film, Grodin has assumed the role of the husband and he's fine (he has a subtle touch which is a nice enough trade off for Mulligan's manic intensity). And what one can be grateful for is that the play has been preserved in this manner at all. It's a respectable document of a too-long-neglected work by one of America's best dramatists (Herb Gardner wrote the screenplay too, which despite a few frustrating cutting room edits, sticks close to the outline of the play).
The flip side is that the film doesn't lift the material. As filmmaking it's kind of flat and often seems like nothing more than the play being filmed on location, almost documentary style. It is, however, better than nothing.
As others have noted, THIEVES is indeed unavailable as a commercial release (unless you find the rare UK videotape in PAL format). And it should have at least that much life. But it hasn't completely vanished: that selfsame British videotape has been digitized for home-brewed DVDs and can be found on renegade disks sold on certain internet sites by certain internet vendors. IMDb rules say I cannot specify where, but creative web-browsing should eventually lead you to a relatively inexpensive copy. And indeed, that's how I located mine. *I OFFER* you that advice for free.
