He stopped being funny a few years ago from what I can gather. I watched that end of year wipe thing over christmas and bailed half way through. Either the format is stale or he isn't as funny.
For me he peaked with the end of the year wipe 2011, mainly because the news that year had to be taken apart by someone. The riots in london or The Sun scandal for example were perfect fodder for Brooker and really no one else was bothering to take the news to task over the way they handled it. I know it has no effect what so ever but it's good to see some sanity on TV. This year the major story for the last few months was Jimmy Saville which just isn't funny and Barack Obama who isn't exactly a gift to comedians either and the olympics were a huge success. Bet he hated that.
I don't watch TV anymore, I don't own one. Screenwipe is a great reminder of why not. It's not as potent as it used to be though but I think it's down to the material, I doubt when he started and was taking the piss out of Geordie Shore, he ever thought that that shit would still be on 5 fucking years later. It's like Millhouse as Fallout Boy saying "repetetiveness is my job"