I've used the early nanocom which was good, but for programming you had to then plug in a laptop.
I bought the hawkeye, note that they are coded for the defender or for the disco, it won't do both unless you get another unlock code. It is a bit bigger and chunkier, but it gives loads of info. A few wee quirks like when in low box it tells you high & vice versa. It's understanding the data. I plugged mine into my mates 110 and took a list of details of his readings to compare it.
You can do system tests, injectors is a pulse signal, so you will hear it click. Run fuel pump, fuel gauge. etc etc.
Ruari