This is … the fourth straight release not to drop support for any older Macs, a refreshing change after several successive versions that kept trimming the support list. Leopard ended support for older G3 and G4 Macs, Snow Leopard dumped PowerPC entirely, Lion excluded 32-bit Intel Macs, and Mountain Lion dropped anything that couldn’t go entirely 64-bit.
The minimum system requirements, which haven’t changed since the Mountain Lion release in 2012, runs thusly:
iMac (Mid-2007 or later)
MacBook (13-inch Aluminum, Late 2008), (13-inch, Early 2009 or later), (12-inch, Early 2015)
MacBook Pro (13-inch, Mid-2009 or later), (15-inch, Mid/Late 2007 or later), (17-inch, Late 2007 or later)
MacBook Air (Late 2008 or later)
Mac Mini (Early 2009 or later)
Mac Pro (Early 2008 or later)
Xserve (Early 2009)
Read the full review online. Brew a pot of coffee. This is a long read.