Kenwood KDC-BT61U Bluetooth MP3/WMA/AAC/CD-Receiver with Rear AUX/USB Music Inputs and iPod/iPhone Control

Spent a long time weighing up this head unit against similar from Alpine, Pioneer, Clarion & Blaupunkt.

What sold it to me in the end was the wealth of features available for the amount you spend, I won't list them all here, but it's considerably more than the equivalent models from other manufacturers.

As to installation, operation and ownership..

Installation - it's difficult to get it wrong unless someone's already butchered your cars wiring. One thing to note is the aerial connection is JASO or sometimes called 'standard' so will need an adaptor to fit an aerial lead with a DIN connection.
The aerial and external mic connections are on short leads, rather than being chassis mounted. This is a minor irritation as it's more junk to try and find a home for inside your dash.
It has a short loom with ISO connectors on for the main harness, thankfully there's no in-line chokes or fuse holders on it, so it's a fairly manageable. The loom also have bullet connectors on the permanent and switched live wires to swap them around for any VW/Audi owners out there.
There are 6 Phono pre-outs: pair front, pair rear and pair of subs (why a pair?).
The USB socket is on a moderate length of cable that should be sufficient for reaching a glovebox without extension in most installations.
The aux in socket is also on the rear - taking a 3.5mm stereo mini-jack -you'll need to supply your own cable for this though.
It comes with a cage designed to fit the stereo - not all cages are the same so it's worth checking if you've got the tabs on the side the kenwood needs to fit home securely.

Once installed you've then got a whole heap of options and settings for DSP, tuner, Bluetooth, external media and so on. This is mostly done via the volume knob/wheel and 3 of the 4 buttons immediately around it, a small amount of fiddling will get you familar with the philosophy of the menus quite quickly.

The face flips down to reveal the CD slot & eject button - it'll then pull off for storage. Getting it back on can be quite fiddly though, and required a technique that I've not quite figured out yet. The overall feel of the face, knob and buttons is a little plastic-y and locking the face back in the up position required a little more pressure on the catch side than you'd think. This lets the overall experience down a bit which is why it gets 4/5 stars.

Audio performance is quite good - Hooked up to the OEM speakers in my Audi it took a bit of EQ tweaking to get things acceptable, but there are lots of tools to do this:
5 band eq with +/- 9db gain
2 loudness settings
crossover setting for front, rear and subs based on cone size
HPF on front, rear and subs with customisable curve and cutoff
distance based delay for all 4 corners (and sub)
And a whole host more..

Being highly critical I'd say the bottom end could do with a bit more drive though compared to some older head units I've played with in the car, however they do say you need to run the head unit for a while to allow things to settle, so I'll hold fire on full acoustic criticism until it's been run a couple of weeks.

It looks really quite good - the pictures here don't do it justice - the 'full variable colour' display give you a bunch of presets (and a full customisable preset) which you can set for the display and the buttons separately - this I like as I can get it to mimic exactly the red & amber of the dash in my audi - it'll also do revolving colours or change them in time to the music if that's your thing. Part of the wiring loom involves a connection to your dash lighting, so when you switch the car lights on it will dim slightly - not very much though - it wasn't a problem in my case. The whole front of the unit is glossy black which can lead to reflections and poor viewing under certain conditions, probably more of an issue with convertibles and cars with very light interiors.

The bluetooth paired happily with my Nokia X6 and the wifes Blackberry after a little fiddling- we're an apple free household so can't comment on those features. It'll connect to both simultaneously and can be set to pull music from one whilst acting a hands free for the other if required. It also appears to have no problems with getting contact from the phones too, though I've not tested all the bluetooth features yet (such as SMS and voice dialling) Once set to auto connect simply being in the car with the phone's bluetooth transceiver enabled will allow it to connect.

Radio reception is quite good - manages to pick up some 'not quite local' FM stations without to much disruption to the signal and the multi-line display does a good job on the radio-text if it's broadcast - it'll also set the clock automatically if it gets a radio signal.

Included in the box is also a small remote control that if nothing else gives you numeric keypad for direct entry of phone numbers or radio frequency

Overall I'd say the areas that need improvement are:
Tactile feel and perceived build quality of the removable face.
Face-removal mechanism
Viewing in bright light

Being really picky I'd also say:
Greater levels of dimming on the display
Better low frequency response.

If the above was sorted it's get 5 stars.

USB cable to iphone on this unit work only with music. If you want to use to do phone call it will be necessary to do by Bluethoot. But the issue is that BT and USB does not work at same time.

As Kenwood feedback there is no firmware update planned for this:
"This problem happens because the iPhone tries to stream the music whenever it detects Bluetooth connection; rather than route it through the iPod cable.
So there is no software update from Kenwood side to remedy this (if this is the problem you are experiencing)"

I wanted to replace my original factory fitted system (VW Golf mkIV - Gamma) with a more up to date unit with more functionality. After ensuring that I purchased the correct cable adapters I gave myself a day to do the install (microphone in the headlining, USB in the glovebox, etc), but I did it much quicker than that, probably 4 hours.
I can honestly say that the unit is a fantastic peice of equipment. It is customizable beyond belief with regard to the display and audio settings, and the functionality is excellent.
The only slight negative is the inability to randomly play all the contents of the USB device, but if you have a bluetooth MP3 player, this is not a problem.
The delivery from Amazon (via Dynamic Sounds) was also excellent.