I'm not a fan either. It's a major nerf to all AP mid laners. Why they chose flat Mana and killed CDR is a mystery. Their "goal" was to help mages for the MYMU. Instead they just killed them all. All the changes hurt/cripple/kill any chance of being relevant.
While all of it looks bad, it may still be possible to play AP mages. I'm saying "possible" because it'll almost guarantee we need to rework our builds. The new Hextech items look....okay and plausible. The new staff/scepter isn't that bad. I feel like it could a new core item.
What also hit me was this is all on the PBE. Things are always changing on the PBE. So there's a good chance Rito is only doing this to get a community response. Then before the MYMU actually happens, they put back CDR and things they removed. I'm definitely going to keep an eye on Surrender@20 from now on.