At my previous two companies I've found that HipChat is generally much more accessible to non-engineers. Ideally there aren't multiple communication tools for the same purpose, so I'd rather have HipChat than AIM + IRC.
Additionally, it has some nice features like cross-device chat history, various embed support, etc.
I can see the accessibility to non engineers being slightly better. At the same time HipChat does horrible things with XMPP support, so unless you are using their client, you are in trouble. Also, if I remember correctly their client does not support other chat protocols, which means I'd have to run two separate chat clients, which is increasing the number of applications I normally run by 33% (chat, terminal, browser). I can see its value, but I cannot recommend it over IRC or just your own jabber server.
Additionally, it has some nice features like cross-device chat history, various embed support, etc.