Overall I think it's a great car. It's obvious that the new Z4 shares a lot with the current LCI 3 series designwise. I just wish that BMW will consider adding LED turning lights now rather than later during facelift. The white plastic side indicators looks sort of out of place with the rest of the car (watch the videos and you'll see what I mean). I think the one on the E92 M3 will look good on the new Z4. I agree with others that the standard 17s are a bit small for this car, and I'm a bit worried about boot space given the hardtop design.
As for the interior it's refreshing but at the same time very familiar. The extended leather option gives the car a very luxurious appeal. I feel like it'll only take me ten minutes or so to get to know all the buttons on this car coming from my 3 series. I'm sure it'll handle well and I look forward to seeing it soon.
The BMW 3 series...the ultimate driving machine for 30 years and counting!!