Excellent piece of equipment for someone like myself who has a wife who also rides a bike. I wanted something that would enable us to communicate easily, especially when riding somewhere different to our usual patch so that we could make sure that we could keep each other on track.
Range is excellent and pretty much as the manufacturer says, as is the battery life which I have personally found to be slightly better than the blurb.
I've connected mine to my Garmin Zumo 550 and it works well. My wife has a Tom Tom Rider 2 and also has no issues.
Mobile phone connection is a bonus and when I've used it I have been able to hear and speak without much trouble at all. I don't listen to music on a bike because I prefer to hear what is going on around me, but I would imagine from what I know using the Garmin, you would be able to get some bearable sounds from the Scala if you wanted too.
I do note that one reviewer says that he could not hear the Scala very well. I think that is more to do with the helmet and bike than the Scala, which is plenty loud enough. It does make a significant difference where you exactly fit the speaker because even a small bit out and you lose the sound level. Some helmets allow better sighting than others as well. On my Arai RX7 the space for my ears is deep and perfectly located for the speaker. On my Suomy it's really not much use as the gap is too small and to get a comfy position for the speaker without putting it out of direct line.
Other issues of course are just how noisy your helmet and bike is. If you ride some sports bikes with a noisy helmet then you might have trouble. On my ZX10R with a RX7 helmet - no problems. On a Triumph Tiger with most helmets - no problems. Same couldn't be said when I used my Suomy with the ZX10R, but it was okay on the Tiger. Basically if you have a really noisy helmet and a bike with little wind protection then you might have a some hearing issues.
Charging is fast and the build quality is really good. It's one of those items that feels just right if you know what I mean.
Overall I wouldn't be without it when touring or going somewhere using a sat nav.