For film fans, a Martin Scorsese picture released in the middle of February is like manna straight from heaven. A month that’s usually reserved for the dregs of the barrel, like “Valentine’s Day” and “From Paris with Love,” featuring a film from one of the masters of American cinema? It’s got to be too good to be true.

And in a way, it is. It’s no secret the Scorsese of the 21st century doesn’t hold a candle to the Scorsese of the 20th — anyone who proclaims that “The Departed” is a masterpiece must not have seen “Taxi Driver” or “Raging Bull” or the underrated, surreal “After Hours.”

So, evaluating “Shutter Island,” Scorsese’s latest, based on the novel by Dennis Lehane (“Mystic River”), presents a bit of a quandary.

Is it a good film compared to everything else on the theater marquee right now? Absolutely.

Is it a good film compared to Scorsese’s output from the last 10 years? Yes, and it’s probably his strongest achievement from that time frame.

Is it a good film, period? Well, sort of. It’s certainly an effectively engaging psychological thriller with flashes of the cinematic brilliance one hopes for in a Scorsese film. Still, there’s no getting around the fact that the film relies far too heavily on a telegraphed gotcha twist ending that relegates it to the one-viewing-only pile.

Scorsese’s go-to guy, Leonardo DiCaprio, stars as U.S. federal marshal Teddy Daniels, a World War II veteran investigating a federally funded mental institution on a rock in the middle of the ocean in 1954.

Paired up with a new partner, Chuck (Mark Ruffalo), Daniels is determined to get to the bottom of a missing patient case — a woman (Emily Mortimer) who drowned her three children and has seemingly vanished into thin air.

The two marshals run into their share of difficulty, primarily from head honchos Dr. Cawley (Ben Kingsley), known for his unorthodox methods of treatment, and Dr. Naehring (Max von Sydow), who has German roots that set alarms off in Daniels’ head.

With no answers to the mystery forthcoming, Daniels and Chuck soon find themselves trapped on the island thanks to a hurricane, and Daniels begins to suspect that the man who killed his wife (Michelle Williams) may be in that very same institution.

Scorsese develops a very measured sense of pacing that reveals little, but remains interesting. However, it’s clear from the start that the film is setting its audience up for a surprise — and frankly, there aren’t many options as to what that’s going to be.

As a series of homages — “Shutter Island” is steeped in a ’50s noir atmosphere — the film succeeds in a way that most wouldn’t, as most contemporary directors don’t have a tenth of the film history knowledge that Scorsese does.

And when it deals with Daniels’ interior life, “Shutter Island” is riveting. His hallucinations and flashbacks have a photographic richness and emotional resonance that just isn’t there among most of the labyrinthine plot machinations.

Then there’s the film’s final flashback — an extended sequence that gives us the truth once and for all. It’s a horrific, beautiful, heartbreaking and long section that is masterful, and something most directors would’ve communicated in a series of quick edits and shocked faces. Scorsese lets us savor it, even if we don’t particularly want to.

At its best, “Shutter Island” is a reminder of the gift to cinema that Martin Scorsese always will be. He’s on the downward slope, but plop him down in the middle of February, and it seems like the golden age all over again.