How can a Lotus Domino server help to a small business?

We know about "Lotus Domino server" & it have good reputation but I'm not familiar with it so much. We are running a small IT team & very busy with project related works.
How can a Lotus Domino server help to run a small business? If we use it how much security it can provide us? It is safe for use?
I expected my answer form experience person who already use it & know more better about it?
Thanks
