If you make a living on the phone, this is crucial software. The developer is attentive and top notch. Every time I've had a problem, he was there to address it, within hours. He has also added a feature or two based on a special request.
I have it running on a computer that's tucked away in a closet. It monitors several phone lines and places an entry into Calendar & Daylite, documenting the call (received or made) date, time, duration and CID info. That alone is worth the subscription.
There are many more features for "power users" but that automatic call documentation is my personal favorite.