It doesn't look like hackers are necessarily the intended audience, but it would have been interesting to read about some of the failsafes preventing this system from causing overdoses or other dangerous conditions.
So if say the blood glucose sensor delivers faulty measurements (that happens frequently in my case) it may gradually try to kill me, but it takes hours to get me into a dangerous zone. This is a lot of time for me to notice and correct. I mainly like the system for correcting while I sleep. I wake up less to a low sugar thanks to the software suspending insulin delivery, and high sugar at night is often corrected by the time I wake up.
I don't know about failsafes on the lower levels. I kind of trust it after a year on OpenAps :-)