Pros: Clear alerts, good windshield mount
Cons: Average Ka range, no real advantages over similarly priced detectors
Rocky Mountain Radar is a company you either trust or you don't. Their passive radar scrambler technology has been tested and shown not to work by some but sworn to work by others. I personally can't verify this for you. What I can do is give you the facts about what is one of their newer detectors.
The RMR-C475 is an update to the previous RMR units such as the C450 and is one of their newer models, only the Phantom T and Moto Raptor are newer, the latter being intended solely for motorcycles. It takes their standard radar detector/scrambler and adds a text display to replace LED lights. Otherwise the normal operation is the same. You still get X, K and Ka bands, as well as VG2 detection and your radar/laser scrambler.
First about the scrambler. What the unit does is take and mix the incoming radar from the police and mix it with white noise, then reflects it. The antenna is about 2 inches square. I can verify that it does indeed emit some sort of noise that can be heard on a radar gun at close range but that is all I tested it with. The laser scrambler consists of 3 diodes. I don't believe that 3 diodes is enough to jam laser through a windshield.
As far as the detector. It is fairly standard, with highway and city modes to adjust sensitivity to those settings. I drove with the detector from New York down to Mississippi including going through Ohio where they still use X band. Its range is pretty decent on X and K bands. You'll get a warning plenty adequate to avoid a speeding ticket. Ka band however is probably about as good as $100 or so Cobra. In most cases it is probably sufficient but at $200 or so it could be better. RMR's own Phantom T is much better in this department, with many switching to Ka band it might be wise to upgrade to the more expensive model.
Other things of note. The windshield mount of this detector is great, positioning the detector perfectly, and well designed to hold its perfectly level. For those worried about stealth performance it does emit Ka detectable by other detectors such as a V1 so the Spectre probably can detect it I wouldn't use it in Virginia or any other state where detectors are illegal. As far as a the scrambler, whether it interferes with radar or not it does interfere with CB radio antennas located in close proximity to it. You'll hear an annoying whooshing sound. If you intended on using the scrambler function it might require repositioning of the antenna. The text display, while easy to read at night can be washed out in bright sunlight. The voice warnings are clear enough that this shouldn't be an issue. You won't be glancing at it unless you're running it in dim mode on purpose.
Overall you're getting an ordinary radar detector with text display and promises of a radar scrambler that I wouldn't rely on. Performance is on par with $150 or so radar detectors. If you get it at that price you could take the scrambler functions as an added bonus and enjoy the nice windshield mount.