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Question: Why can't I see the screen of my Garmin 665 in sunlight.  Isn't that what they are for?  I have two, both with the same problem.
Document: Purchased a 665 a month ago. Third day of use the XM tuner would not connect to the unit. Turns out the cable is faulty and is being redesigned by Garmin. After numerous phone calls and emails with Garmin product support, they can't tell me when the problem will be fixed. Currently, I have over $1000 into the unit, the XM doesn't work, and Garmin can't tell me when it will be fixed. Don't buy unless you can be assured the cabling has been fixed.
The 550 has a sturdier feel and also, the size of the screen is easier for me to follow. The 550 is much better in bright sunlight as well.I returned the 665 and bought the 550.
I lost my Zumo 550, so I thought I would replace it with this 665. I did register for the Navigation and the Weather Satellite coverage. The moving radar feature for the 665 was pretty cool. My disappointment lies in the display of the map, whcih is virtually impossible to see during bright sunlight. Also, the unit desided to "faint", or black-out during some functions, such as re-routing (full battery and plugged into external power).
I do not think the cable hardware is the issue. I believe it is the software. I experienced the same problem once before I left on the trip and was told by Garmin Tech to perform a hard reset of the unit by holding your index finger on the lower right corner as you turn the unit on until you see the message that "a reset will erase your data". You have to select "yes" or "no".
The Garmin guy was indignant and argued otherwise but to no avail. At the Garmin rep's insistence, the XM person opened a service ticket and told me to call back within 48 hours.Well, I called back. Result? "Nothing we can do, sir." Your unit will not support the Nav features that you are requesting. "Sorry. "Okay, back to Garmin. After speaking with two more people, both told me "We've never seen this problem before."
The 665 is a good GPS, "whenever it decides to work". I've been through 4 of them.... They all had the same problem, the map animation on the screen disapears in mid use. The voice instructions work, the icon is there, but no road whatsoever. Your icon is floating in white space. The first 665 I bought was factory refurbished. It started acting in this erratic way, I called tech support and they walked me through reboots, updates etc.
There are a couple of "shields" that block the sun, so I might acquire one.In Summary, the 665 is a worthy next generation motorcycle GPS system. The three negatives are mostly being picky (I can see why Garmin did the change in wiring, and it does make sense), but the positives are outstanding. And although this is a motorcycle designed GPS system, it does well in a car too.
So far, they have replaced the motorcycle mount to no effect. It still has the same antenna error.The GPS on my bike now is a Garmin GPSMAP 478 with a GXM-30 antenna. I have had this setup for at least two years now and never had a hiccup.Save yourself a bunch of aggravation and don't get the Zumo 665 and expect the XM to work. Buy the 660 if you must, and listen to the radio...
I have been using the Garmin z&uuml;mo 550 for about 2 1/2 years on my motorcycle, extremely satisfied with its performance and quality. I decided I wanted to "upgrade" to the z&uuml;mo 665 for a few reasons:  first, the slightly larger screen gives more detail and is easier on my eyes. Second, the motorcycle cradle on the 550 was a difficult design, requiring me to add a Touratech bracket to secure it better.
I'm well pleased with the Garmin 665. It is a touch screen GPS with Satelite radio which is waterproof for my Honda Goldwing motorcycle. This unit is capable of receiving weather and traffic information which is handy on a long trip away from home.
Answer: Mines installed in a fairing and i can see it fine 90% of the time unless the suns at my back just right.