Spoent an hour or so on the beta this morning as I received an invite email last night, it's very polished and despite the depth seems a lot more accessible than say SimCity 2k, much easier to understand how thinks like sewerage, pollution, etc work. Zoning is rather odd though, I can't tell how I'm supposed to be laying out roads etc for maximum land usage as you can only zone along the roads and not in blocks.
Overall I think it's going to be one of those you'll lose days to, but not for the £44.99 / £64.99 price tags they want on Origin for Limited or Deluxe versions (ooh, fancy British double decker buses, gee whiz!)
I'll get it when it drops in price.