I have the Navi system and radio. I don't know if the radio is the same for the non-Navi models or not. I am very pleased with the radio reception. The AM band in particular is very good. I listen to local talk radio on AM in the morning. After reading other posts about poor reception but prior to taking delivery of my Ridgeline, I thought that I would need to mount a conventional mast antenna to get decent reception. It is not necessary. I live in the mountains of central PA and local AM stations are usually listenable for about 35 miles. In comparing the radios in my Ridgeline to my wifes 2002 Accord (which I consider to be outstanding and the best radio reception I have had) and my previous 2000 Blazer, The Ridgeline has proven to be by far the best of all. I recently took a 125 mile trip that I would have expected to completely loose signal after cresting a mountain about 30 miles from home. Not only did it not drop out as expected, it remained strong, loud and mostly clear for and additional 30 miles. That range is far beyond any other radio in any vehicle that I have owned. It was a pleasant surprise.
I can not speak to the FM performance since I have not used FM very much at all. I usually listen to XM radio. Even the XM radio drops out occasionally when the road goes through deep ravines. It also cuts out in a few locations downtown when in the shadow of very tall buildings or when driving directly behind Penn States Beaver Stadium. Of course a lot of things that have been going on in that stadium in recent years tends to suck the life right out of you too. The XM radio cutting out once in a while is not a complaint about the radio. It is simply the nature of the beast. If the antenna can not "see" the satellite for more than a few seconds due to terrain or obstructions, it will get quiet until the signal returns. No big deal.
I find the tone quality and presence of the system to be pretty good. Like someone else stated in another thread, not bad, not great, but not bad enough to consider major changes or ripping it out entirely. At higher volume levels it is much better, bordering on very good. Do a few searches of radio topics and you will find a lot of great information, great ideas for improvements, and a lot of varied opinions as well.