The menus are a pain (if only every company used Nikon's method of a two-button card format!), but I haven't really delved into them since setting it up to my specifications.
Buffer time is still absurd, but with a UHS-1 card much more manageable. I've noticed that my GRD IV is kind of slow, too - I don't have any experience with small cameras or SD cards other than these, maybe it's just an issue with size.
AF-wise, I pretty much only use the EVF so I haven't had any issues. I like the concept of the OVF w/ overlays, but I can't see any advantage to it except in very low light (for me, of course).