Good
You can do all sorts of fun things with nmap - like attempting to "fingerprint" the TCP/IP stack being probed, which I once tried on a Speedtouch Pro (the original Alcatel Speedtouch router) and was stunned when nmap identified it.
As an aside using nmap (even on your own network) in the UK is likely to be illegal in a few months thanks to the parasitic lawyers which seem to permanently comprise the UK govt. I intend ignoring this law as I ignore all clueless laws - frankly who the hell can keep up with Neu Liebors "new law a day" anyway