A lot of pop musicians write their songs using just three or maybe four basic chords. But Regina Spektor is no ordinary pop artist; a classically trained pianist, she favors a unique sound that's distinctly more complicated than most stuff to be found on pop radio.
Her first piano as a kid in the former Soviet Union was an upright Petrof. In the piano world, Petrofs are unsung heroes. First crafted by Antonín Petrof in Vienna, Petrof pianos are made in The Czech Republic and are the Steinways (http://www.steinway.com/steinway/) of Eastern Europe, but cost a fraction of the price. Basically it's like buying a fully-loaded Mercedes-Benz for the price of a Honda Civic. Good deal. Not only are Petrofs incredible pianos to learn on, with the weight of the keys, and their polished sound; they're also used around the world in concert halls and orchestras, so it makes sense that Regina is so comfortable onstage with any kind of concert piano. Also, the works of the great classical composers just don't sound right on a plastic keyboard or some cheap model, so we're glad Regina learned her notes on a Petrof.
From the beginning, Regina was classically trained in the works of the great masters, which left a heavy imprint on her musical style. Years of practicing and refining scales, chords, music theory, sight reading, and, of course, learning some of the most technically difficult pieces ever written by the likes of Chopin, Schubert, Debussy, and Liszt will certainly leave an impression. Spektor's songs, therefore, tend to be rich in cadence, tricky fingering and rhythms, and are often written for difficult keys. (Just to give you a contrast, consider "Lean on Me" by Bill Withers, a song you've probably heard dozens of times. The entire song consists of about four chords entirely in the key of C Major; the song is stunningly easy to play.)
"Samson," on the other hand, is in B Major, arguably one of the toughest keys to hit. With five sharps to contend with (the black keys on a piano), B Major is a key rich in melodic texture and complexity and is perfectly appropriate for this song, which is at its core a rocky love story. If you check out some of the YouTube tutorials on how to play "Samson," you'll see just how difficult it is. One guy literally spends eight minutes teaching music theory before even attempting to dive into the notes. Another guy tries to explain how to play the song by saying, "OK, put your fingers here and here"—but it gets messy pretty quickly since you really need to be a trained musician to even comprehend the chords.
B Major is also interesting because it sounds a little bit like a minor key. The main difference between major and minor keys is the mood they give you when you listen. Compare "Lean on me", again, (C Major) to "Colorblind" by the Counting Crows (A minor).
They both have no sharps or flats but the two keys couldn't sound more different. Major keys are bright and uplifting while minor keys are sad and depressing. "Samson" has the dark richness of a minor key with the light cadences of a major key; the choice of B Major (coupled, of course, with Spektor's amazing voice) makes the song truly beautiful.