For what it's worth...I bought one about a year and a half ago. No, it's not spectacular, but very good, especially for the price. The contrast is a little low, which shouldn't matter for digital, and it didn't look so great when shooting close. I wouldn't recommend it if you're going to use it as your primary portrait or table-top lens; there are better tools for that. But if you want something to try for the occasional special effect, or special situation, without sacrificing quality, this could be a good way to go. This is much more than an overpriced Lens Baby.
Remember that the lens uses stop-down metering and lacks autofocus. That's not a big deal for cooperative subjects, and I assume your full-frame Sony will allow for good manual focusing. For me this old technique creates two issues: First, I develop a shallow bruise on my leg after kicking myself for forgetting to stop down the aperture. And, it takes some practice to gauge how the in-focus and out-of-focus areas are going to read in the final product, assuming that I'm using lens tilt or swing for that effect (or correction). If you ever used a loupe on a view camera, you'll be pining for the day when you could stop down and get right in on the ground glass to really see what every area of the picture is going to look like. Live view might help out a bit, but for me, those little screens are never quite the same.
Note that the tilt and the shift are locked in opposite directions. So, if you tilt your lens downward, for instance, you'll only be able to shift, should you want, to the left or right. I think of the lens less as a "tilt/shift" and more of a "tilt or shift". Sometimes I can use both together, and just consider it a bonus.
If it turns out you don't use the lens so much, I imagine it would be fairly easy to sell on the used market. That should mitigate your investment risk a bit. MB
