Three things are very much of note in “The Cake Eaters,” now showing in the Screening Room on Sheridan Drive in Amherst:

THE CAKE EATERS

Two and a half stars (Out of four)

STARRING: Kristen Stewart, Bruce Dern, Elizabeth Ashley, Melissa Leo, Jesse L. Martin,

Aaron Stanford and Jayce Bartok

DIRECTOR: Mary Stuart Masterson

RUNNING TIME: 86 minutes

RATING: Unrated, but PG-13 equivalent.

THE LOWDOWN: Three small-town romances center around a dying young girl and a family in mourning.

1) The central performance of young actress Kristen Stewart, of “Twilight” fame and soon-to-be-ballyhooed next week in the film “Adventureland,” one of the few sexual coming-of-age films that’s actually as sensitive, funny and veracious as it wants to be.

2) The appallingly rare chance to see a man who has been one of the best film actors we have for 45 years: Bruce Dern.

3) It’s the film-directing debut of fine actress Mary Stuart Masterson (“Fried Green Tomatoes,” “At Close Range” and TV’s short-lived but nicely pungent “Kate Brasher” from eight years ago).

It’s the first two, frankly, that are most memorable. Stewart is a superb young actress (she’ll be 19 next month), and this is probably the most impressive thing she has yet done on film. She plays a young woman suffering from Friederich’s Ataxia, which makes movement difficult and makes her sound drunk when she talks. She’s as philosophical as she can be about it — “it’s as bad as it’s gonna get, until my heart gives out.”

Which could be any time.

And which is why she wants to have sex with her tutor, a clumsy but ardent young man whom everyone calls Beagle.

As impressive as Stewart is in this film, I must confess what a huge pleasure it is to see Bruce Dern again. He is absolutely one of the great living film character actors — and if you have forgotten that, this movie will remind you.

He plays Beagle’s father, whom everyone calls “Easy” for reasons made clear by his wonderfully subtle low-key performance through most of this. Look, in fact, at what Dern does at the same time you look at what Elizabeth Ashley does as his longtime lover. Never has such underplaying as Dern’s looked more artful than when you compare it to Ashley’s excess.

The film is, otherwise, the sort of low-budget indie film that is wonderful in theory but, at times, more than a little painful to watch. There are, after all, limits to how much breakfast debate over the virtues of shredded wheat vs. bran flakes people are willing to put up with.

The music by Duncan Sheik is decidedly sparse, which leaves long stretches of film where the only music is what can be gleaned from “environmental sound” (radios, etc.). As it was in the current “Wendy and Lucy,” it’s a kind of “cinema verite,” which always makes some scenes feel longer.

The script is by Jayce Bartok, who plays Beagle’s older brother, who comes home after his music career falls apart. When he returns home and goes, at first, to embrace the father (Dern) he hasn’t seen in a long time, his father pushes him away and says, ever-so-quietly, “it’s been a long time.”

That is a great American film actor — now all but disappeared from our movies — and a promising director working beautifully in tandem in that director’s first film.

The film is, otherwise, the sort that presumes that because it’s independent and is so beautifully cast (and so respectful of its cast), that you’ll be rapt at every moment.

My guess? You may not.