Some more Mr. Nice Guy is presented for the genial entertainer's army of fans. Of course, there's more fey Coz charm than substance, but that's not really the point when it comes to an amusement concocted more for TV viewers than for bookish folk. The current easy reader from easy writer Cosby follows hard upon his best sellers dealing with fatherhood and with attaining the age of 50. Now the frightening joys and happy frustrations of love and marriage are analyzed effortlessly in a heart-to-heart marked by the surface wisdom of a latter-day, North Philadelphia Judge Hardy. Chronicled is the search of "a wistful boy with a good jump shot and bad skin" for the Holy Grail or, more accurately, a girl. Discussed is Man's guest for "J-O-N-E-S" and Boy's quest to find out just what "J-O-N-E-S" is, anyway. (It seems to have something to do with "S-E-X".) One difficulty in the author's coming to manhood was finding a girl who could appreciate the wonderfulness of John Coltrane, or at least trying to "explain obvious greatness to a foreign sex." Bill's search is finally rewarded with the advent of Camille, his wife, with whom, if the text is to be believed, he swaps dialogue reminiscent of radio's classic Bickersons. There are set pieces about Dad's habit of dropping shoes any old where or leaving the toilet seat up, the male inability to ask directions, methods of sleeping with a wife, and all the comic differences between the two basic models of people. It's a pleasant enough valentine to Mrs. Cosby, but more weight would be even nicer. The nearly unbearable lightness of kidding is the only problem, and an introduction by Alvin Poussaint, M.D., doesn't help at all. It's clearly not meant to be Hedda Gabler or Proustian; it's more Garfield-esque or Peanutsian. Coz has simply handed us another hour or two of the same stuff good sitcoms are made of.