i've had my pioneer avic D3 for almost 2 years now and it's worked flawlessly and i consider it the best HU i've ever had (granted that's not a bunch). i highly recommend their products.
www.avic411.com is also a great source of info about their products and how to hook them up if you decide to do it yourself (took me about an hour following an install guide i found on clubfrontier.org to do mine, first time ever doing a dvd/nav system)