Curiosity piqued, I made a bee-line for a song Frere-Jones rated particularly highly, "I'm New Here" (recorded when Callahan was doing business under the stage name Smog.)
And the answer to your question is -- I don't know about this guy. Which is to say, I haven't quite decided whether he has a genuinely interesting and quirky sensibility or whether he's just a sort of post-modern Gen Y version of a lot of full-of-themselves 60s and 70s poet types I didn't care for back in the day.
Although I gotta admit that this paragraph from the New Yorker piece --
There are other antecedents for Callahan, some of which he rejects. Though he has expressed admiration for Fred Neil, the deep-voiced folkie known for writing “Everybody’s Talkin’,” from “Midnight Cowboy,” and for Merle Haggard, another songwriter who is fond of the comic deadpan, Bob Dylan, the albatross for many songwriters, is irrelevant to Callahan. “I never liked him,” he told me. “He seems sort of unpleasant and uncomfortable.”
-- may have gotten my hackles up to the point where I'm incapable of giving the guy a totally objective listen. At least for now.