How would you write this review?

Please help me correct for a review. I don't know how to say one sentence. I think I've gotten my point across but how would you correctly convey the thought?
What do you think about the bold, how would you say that?

The "find your friend" application for iPhone allows you to track your friend's whereabouts. The only thing wrong with this application is that it's not up to the minute/it's not in real time. If your friend was at home and left, the app might still tell you they are at home and only later tell you that they've left.