Our fert dealer has one and brought it out.  I have very mixed feelings and I am reserving my opinion until I get to harvest.  We took several tests before sidedress and it was telling us that we need between 120 and 150 additional units of N applied.  This was all corn after beans that got 100 units applied at planting.  So our plan had always been to apply an additional 80 units which is what we did but we also left some checks where we applied the rate the soil scan told us to and also left a blank check where the only N application was the 100 units on at planting.  

My initial opinion when we were out in the field was that this thing is really gonna sell a lot of N!! But I really don't want to count it out without giving it a chance.  I can see it being very helpful the year where you have 30 inches of rain April May and June like we did last year but I think there is going to be a learning curve on how to read the results from each test.