Fans of Stephen Sondheim ’s operatic musical “Sweeney Todd” are legion. They know the show backward and forward, and swear by it.

Even though the Demon Barber of Fleet Street’s original Broadway run in 1981 lasted only a year, the show has taken on a life of its own. It is often revived, most recently in a terrific production at the New York City Opera.

So lo and behold, in the last few hours, two cultural things have happened in New York related to "Sweeney Todd": a strange revival opened on Broadway, and the New York Times’ theater critic Ben Brantley promptly lost his mind. To say he loved it is an understatement. He went cuckoo. Read his review. You’ll see.

I saw “Sweeney Todd” at the premiere last night at the Eugene O’Neill Theater. This version comes to us from England, and it sure seems exactly like the kind of production you’d find at London’s Donmar Warehouse. It’s edgy, compact and surreal. Instead of a lavish production with a sumptuous orchestra, director John Doyle has reinvented the entire thing.

It’s like remaking the wheel itself. You’re either horrified or excited when you see the result.

Doyle and music supervisor Sarah Travis really went to work on Sweeney Todd. Doyle is also credited as “designing” the show. He’s thrown out the barber chair, the oven, the picnic tables, the organ, the whistle — just about everything for which the show was known.

He’s pared down the large cast to about 11 people, all of whom play instruments on stage. The backdrop of the one set is a 20 foot high (at least, or so it would seem) étagère filled with knick-knacks that makes the whole thing look like a Joseph Cornell box.

Believe it or not, this is the dark side of “Sweeney Todd.” You’d think a show about a barber who kills his customers would have already been considered dark. But Doyle has found a way of telling the story that makes it much more tragic.

Travis has helped almost in an inverse way. She’s made the unforgettable score more accessible, and brighter. She’s also changed the two most famous songs, "Johanna" and "Not While I’m Around."

The former was never a whole song in the first act. Now it is sung completely by the actor who plays Anthony (Benjamin Magnuson ), and it comes off like the hit it should have always been.

In the second act, the haunting "Not While I’m Around" is no longer a duet with Mrs. Lovett, but now entirely sung by Toby, the crazy kid left behind by the visiting Italian snake oil salesman. Each change is a vast improvement.

Patti Lupone plays Mrs. Lovett, looking very much like a punk girl from the UK circa 1981, very Helen Terry of Culture Club fame. The outfit feels left over from “Taboo.” She wears a severe black wig, and a sparkly dinner jacket. This is not Angela Lansbury’s Mrs. Lovett. It’s more like Tim Burton thought her up.

Michael Cerveris, who played Tommy on Broadway in the rock opera, is a little young to be Sweeney Todd. His voice is grand, but sometimes he comes across as a version of Austin Powers’ nemesis Dr. Evil.

Overall, the new Sweeney Todd doesn’t seem like a show that should be playing in an ornate Broadway house. It begs for a stark, modern environment. The juxtaposition is jarring and takes a little getting used to, especially when you realize the cast is supplying the bulk of the music (Lupone playing the tuba is so absurd that it works).

Sometimes the effect of a stark, raving “Sweeney Todd” seems brilliant. At other times I got a headache. Some people did not come back after the intermission. Those that did, though, got a chance to see the most innovative, if not always enjoyable, show on Broadway right now.