I used to watch the channel religiously. This was back when it had Judgment Day, G4tv.com, Cinematech, Arena, Icons, Pulse, and the awesomeness that was Portal. When they "merged" with TechTV it was the beginning of the end. They cancelled almost all their original programming and most of the TTV stuff, which was depressing for fans of both channels because in one swoop they ruined two good things.
They still had some good stuff for a while. I enjoyed watching X-play, The Screen Savers (and to a certain degree, Attack of the Show until it turned into Bro-fest), and loved Code Monkeys.
Recently though, as many have pointed out, its just been reruns of Cheaters, Cops, and any other shovelware tv shows they could stick on the network. It was a waste. They could have had a decent niche channel with solid ratings but they wanted to have something beyond their grasp and caused the whole thing to implode. Then instead of trying to fix it, it just became a dumping ground while the idiots who screwed it up in the first place tried to figure out what to do with it.
I knew when Adam and Kevin left that the network was on life support.
I hope a the very least they do something like rerun all the classic shows for one final hurray before the channel turns into another generic mish-mash of existing stations. Most likely though they will just change over to the new format and try to make everyone forget the network ever was.
On the plus side, I met and hung out with many of the hosts of the old shows over the years. They were a very cool bunch. I also made many good friends on their forums and we've stayed friends over the years long after we stopped watching the channel.
So RIP G4. You had something special and blew it.