Rerouting dialog is obtrusive
When waze reroutes or changes ETA it pops up a dialog "Rerouting" or "Your ETA has changed due to ...". Especially the rerouting dialog is annoying as it obstructs a clear view of the map which you most likely need at that moment. A small spinner in the corner of your screen (maybe in the green nav-bar?) and the audible warning should be enough. Maybe a "Don't show again" button on those dialogs?