People upset about the damage nerf to Ryze's ult are upset over the wrong thing. AP provides most of your scaling and damage there anyways. The real nerf came from the range reduction of Arcane Prison, which imo went a little too far.
There are enough counters to arcane prison in the game, and given that ryze charging towards you or entering the brush pretty much tells you what he is doing, a shortened range on this ability is devestating to what is already an underpowered hero by mid-late game. Ryze does not farm well, so he does not make much money if he does not kill, and the reduced range on prison (which did not have that large of a range to begin with, at 600; is 550 now i believe), makes it even easier for the opposition to react. He almost makes me think of an evelyn without the stealth component now, since his ranged attack does not have that large a range either at 425. For comparison, Karthus has 450, Veigar has 500, Zilean has 600.
I'm not arguing with the people that say he is rather one dimensional, as in... I walk up to you and smash you and have no skillshots. This is true =p. I'm just saying that Riot has made it overly difficult for a hero with one of the slower base speeds of 300 to do the only thing he does, kill heroes.