The service works well, I can see my location through Google Maps when using it in different countries around Europe (Germany).
Sometimes GPS signal goes off even though you're still moving within range of cell towers! It's hard for me personally because sometimes we go out at night with friends who don’t have this kind of tracking system set up but maybe that would be useful? Definitely use their services so everyone knows what time people are leaving etc.. You will feel more secure knowing your loved ones know how long its safe before meeting them again :) We've used other companies like these which aren't very good quality compared too ours :p.