Twilight. Not because it broke vampires for this generation, not because it encourages girls to think that creepy stalkers are sexy and you should long for soulless immortality, but because they are badly written, and the fact they have been pulbished encourages people who really can't write to try and get published, thus possibly breaking books for this generation.
Ahem.
I agree about Maximum Ride book four, but I actually quite enjoyed Book 5, when he got back on topic. Unfortunately, you kind of have to read book four to get book five, but I think it's worth it (just)
I also think he has a tendency of doing it. The Alex Cross books have reached the point of being highly formulaic, easy to predict, and the amount of gore in them has been ramped up to the point where it now no longer makes sense.