You can finally preorder the super compact 28mm f/4.5 FE lens on Indiegogo (Click here). Here is a first collection of review of the new lens:

SonyAlphaBlog concludes:

The Viltrox 28mm F4.5 (99$ / 109 Eur) , is a pancake with very good performances. Most of the package lack AF, or have bad quality, but this Viltrox is one of the first very good pancake I have really enjoyed to use : very good to Excellent sharpness, very good AF, low distortion, good color rendering, very nice sunstars and a very low price.
The main weak point would be the average resistance flare in difficult situation.

Philip Reeve concludes:

Designing a tiny pancake lens – and offering it at a very affordable $99 – means there must be some optical compromises. And with the pancake lenses I previously reviewed, there certainly were a lot of those compromises – and those lenses didn’t even feature auto focus.
Here some of those compromises are also obvious: fixed f/4.5 aperture, no manual focus ring, no filter thread, high vignetting. But in the field, you may not even notice these on a regular basis. The fixed f/4.5 aperture in fact proved to be less of an issue than I initially expected and I ended up enjoying my time with this lens – something I cannot say about most of the competitors.
So out of all the pancake lenses for fullframe E-mount cameras (I think I have used all of them) this is actually my favorite so far. The inclusion of auto focus also makes it appealing to a broader audience than a purely manual focus lens.