I have tested the wipe on my phone and the process went as follows:
- sdcard (or 'sd' partition if you don't have an external sd) gets wiped while the phone keeps running as usual
- reboot into recovery to wipe the other partitions
In my case the wipe stopped there because I am using full disk encryption (and you need to insert the password at every reboot).
So basically in my case the wipe was silent up to the reboot. Hope this helps.
