The AVH-P4100DVD has arrived and has been installed for a couple of weeks so I thought I'd put together my thoughts on this unit.
Firing the unit was very easy, the connectors hooked up easily and all or the components fitted in the car fine first time with no modification other than the manufacturers fascia kit.

All of the connectors on the back of the unit are very well labeled, even the ISO connector kit. Quite why you still require a Pioneer to ISO connector lead and cannot just plug the ISO's into the back of the unit I don’t quite know in this day and age, but hey it works.

I had to consult the mighty Google to find out how to disable the 'Demo' feature as by this time I’d lost the manual but it’s simply a case of holding down the 'Mute' button while the demo sequence is running to disable. Again why this isn’t a physical switch or jumper on the back of the unit I don’t know. It's a little strange to me why this feature would even be enabled by default as only a handful of shop units would ever need this unit on, in all other circumstances it's just a pain in the arse, but it seems to be the same no matter what vendor you choose.

The interface is very good and easy to use. There is no lag when using the touch screen and all of the menu's are instant. The source menu is also well laid out with bug screen area's to select the desired source. The only thing I could say is when playing MP3 files with long tag's you only have about 20 characters shown on screen of each tag. This is annoying when you have a dozen or so files or folders on the stick called 'Ministry Of Sound - Chillo' as they do not scroll to reveal the extra length, its not like were short on screen space here are we.

At the moment I have speakers hooked up directly to the unit as my Amp's have not arrived yet. The sound quality is very good. The default profile for the EQ is 'Powerful' and this must be changed to Vocal if you only have manufacturer's or crap speakers because the additional Bass will just make them distort at very low volumes. Initially I was unimpressed with the sound quality for this reason until i changed the EQ profile.

The quality and viewing angle of the screen are both very good, the screen is bright and clear in all lights and if your car's ISO supports the dimming connection the screen automatically dims when you switch your lights on.

I have had to disconnect my car's battery to prep the wiring for the Amp's i was disappointed to be presented with a reset unit afterward. Car ICE has come a long way recently and would it really be that hard to have a small battery like in a computers CMOS to keep your settings or have the ability to load and save your configuration from a USB stick?

Radio reception is also quite poor and there is no remote supplied with the unit as it does not have an infra-red receiver, I would have liked an option to add steering control's to the car, my 10 year old Kenwood came with a small unit that sticky back velcroed to the back of the steering wheel but its not the end of the world.

My only other niggle with the unit is the 'Tel Mute' feature only does what it says on the tin. When you receive a call the audio is muted as you would expect, if you are watching a DVD or listening to music it would be nice to have the choice to also pause playback.

When playing MP3's there is a load time between files. This load time is only a second but makes continuous mixed albums impossible to play without interruption, it really needs a cross fader.

Otherwise this is a great unit, it feels well made, the UI is quick and easy to use and it has a wide variety of connectivity options.

To summarize the positive points are:
• Good User Interface
• Excellent Sound Quality
• Good Range Of Playback Standards (MP3, CD, DVD DIVX etc)

And the negative points are:
• No configuration backup battery
• No ability to save configuration to USB device
• Disappointing Radio Reception
• No infra-red remote / steering controls
• Impossible to read long MP3 / Track names
• Telephone Mute does not pause the track / playback
• Lag when switching MP3 tracks

Final Verdict:
I hadn't realized when writing this that there are so many shortcomings of this unit. I'd like to get my hands on a Kenwood to make a comparison, but I suspect the shortcomings may be similar for similar units.

The direct Kenwood alternative would be the DDX8024BT but even with the shortcomings fixed I'm not sure I could justify the additional £300 for the Kenwood.