Pros Bluetooth Speakerphone through car stereo speaker with built in microphone; iPod connector optional but worth the cost
Cons none that I have experienced
Summary This is an excellent product and very affordable - the sound quality is excellent and the stereo unit provides many equalizer options. The unit works great in BMW 330ci Convertible (though I haven't used it yet with the top down).
The bluetooth feature / speakerphone works flawlessly and I have heard no complaints from the other end of the phone. As well, the phone syncs easily (T-Mobile G1).
I also purchased the Sony XA-120IP (iPod connector) which makes the functionality of the iPod through the stereo head unit and/or remote control very simple and safe.
Had the unit professionally installed at Geek Squad; not because the unit was complicated, but because BMW is not an easy install and I didn't want to take the chance of ruining the trim on the car.
The unit is simple enough for any idiot to figure out without ever opening the instruction book (this idiot was able too).
I am very happy with my purchase and highly recommend the MEX-BT5100 by Sony. I shopped for months for a good deal and after extensive research, I came to love this unit over the compatible Pioneer and Kenwood units.
Pros It was very premium on its release date.
Decent sound quality
Cons Lacks usb connections.
A2DP sound quality is not par with quality achieved using CD/MP3CD.
Summary A very nice device that standed out when first released, very trustworthy and never dissapointing after close to 4 years of use.
Pros simple all in one
Cons Have to open the unit to have better mic use for the phone.
Summary I install the unit in a my working truck and is simple, sound is great plays MP3's from CD's only. my truck is very noise and some time I need to talk loud. remote control was a plus but not need it. like the display that is able to change. detachable face is simple. I need to clean the connections now and then. (working truck, lots of dust) no big deal. really low cost.