I brought Skylines a few days ago and I absolutely love it. Its got amazing detail and it's pretty much everything I hoped a modern sim city would be. I never thought I would find building a traffic system so fun, and the twitter feed it uses to show you your citizens opinions is a fantastic idea as well.
The one downside is it gets a bit boring after you have made your city. On Sim City you could at least trigger some disasters to destroy your city in interesting ways, I find myself missing that feature sometimes.
I feel just the opposite. I think they pace the game really well. You are constrained at first, but the early game is pretty easy. Once you get a bit larger traffic becomes a problem and you need to make adjustments quickly.
When you get further along you can create districts and set policies that affect the evolution of your city. I think the late game is way more interesting as there's an endless amount of things you can tweak.
I'm really looking forward to seeing more mods that affect how districts work, I'd love to create a china town or little italy with specialized assets. I think these things are all possible and will make fully realized cities much more fun to tinker with.
The one downside is it gets a bit boring after you have made your city. On Sim City you could at least trigger some disasters to destroy your city in interesting ways, I find myself missing that feature sometimes.