Does it sound like all his other songs?
Newman's songs are heavy on lyrical content. This is in contrast to some other songwriters who rely heavily on exotic and catchy melodies which tend to be much more commercial and friendly to the ears of the masses.
Newman's songs don't tend to be all that melodically adventurous, and therefore are not very commercial, so to some, his songs "all sound alike". Add to that, Newman's rather flat vocal style, which is usually a perfect counterpoint to his sometimes alarming lyrics, and its no wonder some people can't distinguish between his songs and find him lampoonable because of it.
In reality, his songs are only alike in that they are all usually lyrically sardonic, sarcastic, smart, funny, insightful, and present a distinct attitude. These tend to be things that make his songs difficult for the masses. But if you've got some time to really listen, and some...uh, understanding, Newman's songs can be a revelation.
With the possible exception of "I Love L.A.". This song is as on point, straight forward, and artful, a celebration of the city as has ever been presented. One of the few Newman songs where he means exactly what his words are saying.
He is a rare and truly unique talent.