While hardly the most aesthetic and co-ordinated camera / lens combination, this lens is really very good. I've tried it on the Leica M9, Canon 7D and now on the Panasonic GH1. Bought primarily as a lens to provide a relatively fast wide angle option for video, it is an excellent high quality lens for stills photography also.
As was found in the review of this lens on a Canon 7D /soundimageplus/2010/08/canon-7d-samyang-14mm-f28-lens.html there is a fair amount of barrel distortion, the lens scale is way out and the inability to fit filters on the unprotected large front element means care has to be taken with its use.
However, it is a very sharp lens. It is also sharp wide open at f2.8. On m4/3 it becomes a 28mm lens (35mm / full-frame equivalent) and because the edges are hidden in the crop, it only uses the "sweet spot" of the lens. Its actually a very "sweet spot". The lens focuses reasonably closely and is useful for close-ups with out of focus backgrounds.
As with all good quality lenses the point of focus is very sharp. The bokeh isn't bad for a lens of this type also. Considering its price its a bargain. 14mm f2.8 AF lenses are usually very expensive, and while this is a manual focus lens, its still excellent value. As before we are very pleased with its performance, and having taken somewhat of a risk buying it "blind" we are very satisfied, and surprised by how good it is.
Words - D
Pictures - D & A