Sculpt-wise, I think a key issue with the unhelmeted head is the hair - it seems quite tall and the sculpt detail is lacking. I quite like the helmeted head on this release, maybe because the hair isn't visible.
It's interesting that HT and SSC can both produce pretty off-looking hair - HT because the shape is often wrong and the paint, while realistic, is usually a weird color (metallic, or black instead of brown) whereas SSC often does a better overall shape but sculpt detail is poor and apps look unconvincing. Here the SSC hair shape looks a bit off too.
The one issue is that none of these images from the video truly shows how the headsculpt paint apps look - and that's been the key dealbreaker for Sideshow human heads even up to the most recent releases. The Mythos Ben looks on-apr with Sideshow's best recent examples, but they are still not at the level of realism of a HT head.
This one looks to be on-par with with the Snowpseeder Luke - which was really quite decent, but not good enough for a helmetless head that has to carry the whole figure like a Death Star battle Luke.