For anyone looking for an ATX case, I think this is one of the best options available. And perhaps the best option that tries to match silence with quality air flow.
I just put a 4790k build into this case and I really like it. I'm running 4 140mm PWM fans, 3 intake 1 outtake, in addition to the CPU fan, all attached to a Swiftech fan splitter. I haven't overclocked anything yet, nor changed any fan settings as it's quiet and fast enough so far. Fractal did send me some extra feet that I attached to the default feet so I could raise the case to help with the bottom intake.
I also really like the extra space behind the motherboard tray and it has helped a tremendous amount with cable management. I don't have a lot of hardware in my R4 at the moment, but it is the cleanest and coolest build I've ever put together. I'm really impressed with the case.
As to weight, I am coming from an Antec 180 and it is considerably lighter while maintaining a very solid build quality. And I don't feel like I am missing anything in regards to expansion.