I thought Amstell was the beginning of the end to be honest. Lamarr often seemed to have a genuine contempt for the people he ripped into as well as a genuine love of music whereas with Amstell it was all just friendly "outrageous" celebrity bum-licking.
I wasn't convinced that Amstell was the best appointment at first (I loved the, as you say, genuine contempt Lamarr seemed to have for the guests and the show by the end and found it hilarious viewing), but he convinced me by basically being very, very funny. Yes, it did kind of turn into him riffing in a mostly faux-outrageous fashion on the guests that week and the quiz itself took something of a backseat, but let's face it, the quiz format itself isn't exactly the iron horse of the BBC2 schedules, given the ludicrous glut of crap panel shows we've had since it first appeared in (erk) 1996. 1996!
Fair enough if Amstell wasn't your cup of tea (I can understand that entirely), but the fact that the quiz format is basically all that there is now, makes it kind of like a creepy naked shop dummy in a badly lit window of a shop on a desolate high street. At midnight. And it's raining.