Eigen 3.3-beta1 has been released on December 16, 2015.
The source archive is at: http://bitbucket.org/eigen/eigen/get/3.3-beta1.tar.bz2
Since the previous 3.3-alpha1 release, this beta version introduces several fixes, as well as some novel features such as new array functions (rsqrt, sign, lgamma, erf, erfc), row/column-wise lpNorm, LU::transpose()/adjoint() API, support for matrix-free iterative solvers, improved sparse matrix filling and products, and more.
If you missed the major novelties introduced in the 3.3-alpha1 version, here is a brief summary of the most exciting ones: novel expression template engine, fast divide and conquer SVD, support for AVX and VSX vector instructions, more OpenMP parallelism, a LS-CG solver.
Check the page dedicated to the 3.3 release for a comprehensive review of all the novelties and improvements introduced in the 3.3 branch.
As for any beta release, everybody is highly encouraged to test this release on their own basecode and report any compilation issue or performance regression on the bugtracker.