So I caved to peer pressure and hooked myself up with the game, my first impressions on playing it last night are slightly mixed.
On the one hand cities are tiny and missing most of the features from the previous game, a lot of which I miss. The endless talk EA mentioned about how much time and effort went into simulating everything was essentially a waste of their time and resource as the flow and cycle of traffic doesn't feel different from the previous SimCity 4, despite knowing how differently it is calculated, and if that is the reason for the small city areas it was a mistake. Likewise falling back to the old school ceaser/pharaoh style 'walkers' for spreading power, water and health means that you can just be unlucky and have sections without water or 'germy'.
I also felt there was a lack of control with zoning, but that might just be that I'm less used to the roads & happiness (even after 5 hours of play) being the dictator for that. Also there appears to be a heavy drop off in numbers of people that work as your city gets larger, I don't have any hard values but it seemed doubling my population didn't get anything close to doubling my worker pool.
The biggest issues I had were with traffic. Traffic kills cities, as soon as you start getting traffic jams your public transport is screwed and you end up with a spiral as more opt for cars instead. Your emergency services start failing as they can't get anywhere, your industry starts closing as freight is unmoved, your tourist attractions start haemorrhaging money as noone shows up and then people leave, your cash less and have to desperately disable everything in an effort not to fail completely. At least part of that is poor road planning in my part, but it's not helped by the dumb-ass pathing for things that matter. In real life when day in, day out a road is always blocked people change route, and if their expensive complex simulation system can't handle things a basic A* can they need to rethink their goals.
On the other hand, despite everything above, I still spend my whole evening playing it, and I enjoyed it. I think the it helped when I started viewing cities and neighbourhoods and regions as just one big spread out city, but whatever the game is it's fun.