I actually fitted a Bury kit
With the Grom kit you need to disconnect your CD changer, but on the Bury kit you can keep your CD changer.
Also you can wire up your Bury kit to work with Volvo radio's telephone mute feature, so when you get a phone call it mutes the radio and shows either "TEL" or "PHONE" depending on your radio model.
Downside of the Bury kit is that you can't use the Volvo radio controls to adjust volume or skip track when you're playing music from your phone, and music sound quality is noticeably inferior when compared to CD playback.
Overall I'd say it's an excellent kit if you're primarily using it as a mobile hands free. If playing music via bluetooth is important to you then the Grom kit might be a better option.