The two new Zeiss Loxia lenses incorporate proven Zeiss designs into all-metal manual focusing lens bodies for the full-frame Sony Alpha A7/A7R system.
These are the lenses I would choose as a Sony A7s/A7/A7R shooter for most of my purposes (particularly the A7s, for video focusing). Why? Because I like the solidity and long-lasting build quality along with the precision of manual focus. A good manual focus feel/throw is a wonderful thing, and the EVF on the Sony bodies makes pinpoint focus easy and fast.
Both lens designs are classics, and are presumably tweaked to be optimal for ray angle issues and sensor cover glass on the Sony A mirrorless lineup (support for other brands presumably will follow, when other brands like Fujifilm offer a full frame camera).
The 35mm f/2 Biogon originates as rangefinder lens design (Zeiss ZM 35mm f/2 Biogon for use on Leica M). This is the superb lens design used in the Sony RX1 / RX1R (lovely performer there), though it could incorporate modifications for A7s/A7/A7R system. The front element is of a special glass type, but it’s unclear if this differs from the RX1R or ZM variants.
The 50mm f/2 Planar is another classic Zeiss design, presumably based on the Zeiss ZM 50mm f/2 Planar for Leica M. It is a very strong performer when stopped down slightly, and has gorgeous bokeh from its symmetric design.
The main question that arises in my mind is the strategic approach: it’s a courageous move to go manual focus and high quality build in today’s market, and that will attract a certain group of customers on its own.
The marketplace risk as I see it relates to optical performance and pricing relatively close to alternatives. These designs are excellent, but for many users autofocus exerts a strong pull. So some icing on the cake would add appeal: I would like to see something more on the optical front, meaning aggressive efforts towards wide open image quality. Certainly Zeiss Otus quality is out of the question (size/weight/price), but heading strongly in that direction. A higher price point (double) would be needed to meet that goal, but many of the potential customers would find that an appealing tradeoff, and it would establish a clearly separate category. As it stands the Loxia pricing at around $1000 seems to me as a customer to carry the same risks as the Touit line.