i've had the HCB-700 for a while now and is very good a lot more reliable than the HCB-300. The noise supression is good as is the sound relay to the car speakers. Has got a nice display and control panel. However ive got a sony erricson phone so they pair up well, may not be as good with a NOKIA phone. Ive also been told that its best to use nokia carkits with Nokia phones etc. to get the best out of the reliability and functionality.
Ive heard that Parrot are very good as well, they work well with mainstream phone brands...may be worth checking out.