I'd be concerned about an app that shows the current time on a tile. In order to do that and be accurate more than once or twice an hour, it has to be running in the background - not a background task, but RUNNING - all the time, which is opposed to the WP philosophy, which was created in part to save battery. In order for an app to run in the background all the time, it has to be "claiming" use of certain services, like background audio or location services. If that's all it does is tell the time and weather on a tile, I would be highly suspicious of this app, especially if I started having battery life problems. Background tasks only run 1-2 times an hour, which means your tile would only be updated that often, so the time would be wrong most of the time.