Broadwell is a 14nm shrink of the 22nm Haswell that debuted over the summer. Haswell is great from both the processor and graphics side; I love Haswell and it works particularly well on Linux. Broadwell is expected to be around 30% more power-efficient than the already respectable Haswell performance and the CPU will use a Multi-Chip Package design while introducing a few new instruction set extensions and other yet-to-be-announced advancements.
Intel CEO Brian Krzanich said during the earning's call that there was a manufacturing issue with the 14nm process and that it would delay Broadwell's arrival. Intel Broadwell CPUs are now not likely to be in manufacturing until the first quarter of next year.
While Broadwell is delayed, on the bright side, this gives Intel's Open-Source Technology Center more time to work on the Broadwell Linux support. As Broadwell is only an evolutionary step past Haswell and still an LGA-1150 package, there isn't too much to do on the CPU side. Support for new instruction set extensions are already being worked on for GCC/LLVM/Clang and kernel patches for supporting other new Broadwell CPU features are being worked on.
From the graphics side, there's still performance ground to raise against Windows as well as bettering the OpenGL support. In my most recent Intel Windows vs. Linux benchmarks with OpenGL Haswell, the results were mixed. On the OpenGL compatibility side, only with next month's Mesa 10.0 release will there be OpenGL 3.2~3.3 support while the hardware supports OpenGL 4.x and the Windows driver does expose GL4. There's also other features found in the Windows driver but not yet in the Linux code.
Hopefully with the Broadwell launch being pushed back a bit due to the manufacturing problems, the Linux support will be in better shape for when the next-generation CPUs arrive.