Can someone please describe how unite works and what it's benefits are?

You should read the information from RIM and the information on BES (remembering that Unite is essentially a stripped down BES.

Then perhaps ask more specific questions.

It's fun. Share calendar, contacts, files... Server should be online 24/7, but you can decide to share BES calendar entries (or not), enter a specific Unite! entry on your device, Unite! contacts appear in your device's address book...

Up to 5 people, so I'll use it at home.

Cheers
Peter

Be aware that removing Unite from your blackberry is not trivial.

I love it, my wife cant say I never told her about something cause now both our BB's have the same calender. Of course she's clued in to that fact as well so I don't have an excuse when I'm late for her parents All joking aside the shared calendar and contacts are the best parts, the email is a nice plus.