I have used it and so has my company. Personally I find it simple to download, register and use. From a security perspective, again it is very good as the only information kept on their servers is your username, nothing else. We have supplied a number of similar solutions to clients in the past and we have found this to match, if not better some of the other solutions available. From a cost perspective, you will not find a solution such as this at this price.
If you have any further questions, PM me, happy to assist.
Silent phone and text are very good, you will need a BGAN to use this in an area that does not have 3g or 4g, I have a 10% discount code if you PM me you can have it. Best feature is the location service, I use it for checking in with the office on my scheduled reporting times, they can bring up Google maps on the app and it puts a pin in the location I sent from so they know its in approx. the right place.