I loved being able to go to Walgreens, walk into the Theranos booth, and get a $10 B12 test without a prescription. Let me do all kinds of analysis that the standard physicians approach didn't.
But, with weekly B12 readings over the space of two months, there was 1 of the 8 readings that was obviously wrong. As an engineer, I'm used to noisy data so was still able to find the data useful.
Last month, went to Theranos (to one of their blood testing centers, as Walgreens had shut them down by then) and had another done. Another obviously, completely incorrect reading, confirmed by a doctor-ordered test at another lab.
So, even though I love the control they gave me (I could order any of a hundred tests on my own without having to convince my doctor to order it, or my insurance company to pay for it), I think it's best that they go away. Too much of modern medicine is conditioned on the results of a single, unverified test - the assumption is that the lab doesn't have an error rate. At least in my apocryphal case, Theranos grossly failed.
I'll go back to the fantasy land where the other, more traditional labs (that want to charge me $150 for the same B12 test) always have correct readings...