Now uses SynthSeg, SynthStrip, and SynthMorph (deep learning algorithms). These make recon-all more robust and much faster. Technically, SynthMorph is not needed for recon-all to run, but the nonlinear registration can be used in multimodal analysis to map to the MNI152.
The use of SynthStrip should make recon-all much more robust as the old skull stripping method often included extra cerebral tissue.