What seems to happen is that the phone itself gives one ring, then sets off the caller ID announcement, at which stage you can answer by pressing the track up button on the head unit.
I am happy with mine, the fact that it integrates with the head unit, is hidden away, gives BT music off the iPhone, and can be used for calls is good for me. I am sure you wouldn't regret getting one.
When I was looking for a phone/ music solution I had 3 possibilities - Parrott, Bury, or the Mediabridge.
The parrot seemed to have a lot of reliability issues, I had one a few years ago, and it never used to work properly.
The Bury, has an external display. I have one of these in our Rav4. A good piece of kit, but an extra display to mount somewhere.
The Mediabridge- just integrates without too much fuss.