5K now standard for 27" models. http://www.bit-tech.net/news/hardware/2015/10/14/apple-refreshes-imacs/1
Spinny rust is a bit of a let-down given they spin the iMac as a premium item [as is the slight nerf of the 1TB SSHD], the SSHD should probably be the default option now. No Type-C USB seems a bit rubbish though... The new peripherals - still hate the design [no change there], rechargeable [about time], communicates over wire when wired up [nice touch], and being 'regular' USB means you can't charge them if you have a retina Macbook without an adapter [though they're admittedly not the target market of the peripherals]
The screens are universally excellent, which is nice news. Only downside is the 5,400rpm HD in the base 21.5" model and the slightly downgraded Fusion Drive if you get the 1TB version (the 2 and 3TB options still have 120GB SSD cache).
