Posted to Amazon on December 18, 2013.

This review is written from the perspective of an iPhone user. I've had this radio in my car for almost a year and I like it very much.

Let me first get AppRadio issues out of the way, and then I'll tell you why I like this product regardless. AppRadio is a feature where your phone runs an app from Pioneer that replaces the user interface on the radio. What you see on the phone is little more than AppRadio logo, and what you see on the radio is the graphical user interface the phone generates in response to your pokes and swipes on the screen (which are conveyed back to the phone over Bluetooth). It's a neat idea with a convoluted and bothersome implementation. In my opinion it fails utterly.

Why does AppRadio fail?

The video signal from the iPhone isn't digital, it's transmitted over a VGA connector (via Apple's Lightning to VGA adapter and a USB/VGA adapter from Pioneer, both sold separately). It feels like you're looking at an image from a 1982 VCR.
AppRadio is all about displaying a video signal from an external source (your smartphone). Accordingly, every time you enter the car or switch to AppRadio mode, you have to dismiss a safety disclaimer *and* apply and release the parking brake to confirm that you won't kill yourself and sue Pioneer. These constant interruptions (and the frequent "please launch the app" messages) ruin the experience and make it seem utterly mickey-mouse. There are safety bypass techniques that can help, but none that really solve the problem.
Native iPod integration (which I praise below) goes away completely. You have to use the Pioneer media player app, and it's terrible.
No iTunes Radio support.
Weak selection of third party apps.
No multitasking with your phone. If you're running the terrific Waze navigation app and have it displayed on the radio's screen, you can't use the phone to do other things, like play iTunes radio or select from your music. You're locked into the terrible AppRadio interface.
The touch screen on this particular radio is resistive, not capacitive. That means it's not responsive enough to control apps as fluidly as one is used to on a phone. Scrolling is a nightmare. And of course there's no multitouch.
The "AppRadio or no AppRadio" question is a hardware decision. You can't decide you hate AppRadio (as I do) and simply not use the feature: you're locked in unless you rearrange the connections behind the radio. If you're not an installer or comfortable tearing into your dashboard to switch modes this will be problematic.

So. AppRadio bombs, at least for iPhone users. A quick check of the Apple App Store reviews of Pioneer's "AppRadio" app confirms this. Pioneer is to be complemented on providing firmware updates that help with iPhone 5 and iOS 7 compatibility, but there's still a lot of work to do, and this is not the revolution in car entertainment they say it is.

----- End of Appradio Rant -----

Hence, I keep my phone in a ProClip mount, safely accessible while driving, and I use the phone for navigation. My four star rating pretends AppRadio doesn't exist, otherwise this would have been a one-star review. Here's what I like about my AVH-X5500BHS:

Great sound. I'm driving my factory speakers with no additional amp and I'm happy.
As touch-screen radio interfaces go, it's pretty well done and not overly goofy.
iPod integration is good if not great. It's not hard to use the radio to control playback.
HD radio is a great upgrade from the analog FM you may be used to.
Steering wheel integration (via an aftermarket adapter) works well.
Bluetooth call quality (via a professionally installed microphone) is outstanding. Even with substantial amounts of road noise, the microphone is good enough for me to dictate texts and e-mails while driving. Spectacular.
Siri works fabulously. Hold the main menu button on the radio for a few seconds and voila.
Looks good. Just a big screen with a few unobtrusive buttons. Nice display customization options.

And here's why I didn't award five stars:

Sporadic firmware support. The last update was August 2013 and delivered support for iPhone 5, 10 months late.
Sluggish user interface. For example, tapping the "shuffle" icon can take a second or two to register, and sometimes doesn't register at all. When a new song starts playing and album art is being retrieved, the unit is too busy to skip tracks or respond to other input.
The MIXTRAX feature is ludicrous. And it doesn't work properly when used with any source but USB (can't crossfade/overlap). Fortunately it can be turned off and ignored forever.
No ability to set power-on volume. If I turn off the car with the volume blasting, I'm in for a shock next time I go somewhere.
No speed-sensitive volume adjustment.

Quibbles aside I'm very happy with this product, despite AppRadio's failings.