I feel similar to you. For years I've admired Kermode and his way of reviewing films, and still look forward to his shows on the radio. However, lately his Five Live show has really been concentrating on what I find less worthy of Kermode at the expense of film reviews. So much time now is spent with forced ranting and raving (fair enough in moderation, but too much of a "good thing"...), his love-in with Simon Mayo and the subsequent distractions from reviews, and the inability to know when a joke has long gone past its sell-by date (the now really boring bringing up letters from the listener who seem to all need to put their educational "achievements" at the fore of their letters; for God's sake, just quit it, it was mildly funny at the beginning, but it's now just pointlessly wasting good time...).
Another thing that neeRAB to be said is that Radio Five can't seem to devote a proper hour to this show, with constant interruptions about some minor sport, pointless press conference, etc, which seems to break up the show. You know, there are hourly and half-hourly news breaks for such stuff, as well as another radio feed on digital.