I've been a Garmin fan for a long time. I've owned several portables and have built an extensive collection of routes, waypoints and tracks in their MapSource application. This spring, I upgraded the old Raytheon gear to a 5212 with HD radar. It was compatible with all of my personal data, but had I not already invested in Bluecharts for the portables, I wouldn't have had any maps to work with on the computer. Garmin just addressed that issue with the introduction of HomePort plotting software. ($29) HomePort is capable of using legacy Bluechart data, but more importantly, can also access map data on an SD card that's either purchased from Garmin for greater detailed, or copied directly to the SD card from the unit's built-in maps.
I'm still getting used to HomePort - I have to retrain myself to deal with a few of the new features, but it's basically the same outstanding application that I've been using for years. I highly recommend it to all Garmin owners.
I've had varying experiences with Garmin tech and sales support: from outstanding to ridiculous. Overall I'd give them a C+, but my negative experiences have all been licensing issues, which I haven't had to deal with now that I have built-in maps.
I used Unkle Buck's Furunos this summer, and I have to admit that having dual screens is pretty cool. I didn't have as much dash real-estate as his 45 had though, but I've been ok with the single display. I like radar overlay much more than I thought I would. Those Furunos struck me as having crisp screens and a faster refresh than my Garmin, but the interface is nowhere as user-friendly. (but then, NOTHING else is, imo)
Garmin's continual updates and improvements are a big selling point for me. They're constantly improving and support their product line, and the system updates are free and simple to apply. Add to that an inexpensive, powerful and easy to use plotting program and the friendliest units on the market. Their competition has it rough.