Waze is technically illegal in France from what I believe, but I've used it for years and find it great. Only thing I've noticed is cameras show as police not a camera that is it.
Nope, it's not. Indeed, you will find that many organisations here are partnering with Waze for directions to events - for example, the ACO for this year's Le Mans! Speed camera/radar detectors or any database of camera locations is illegal here, but Waze gets around this by having an 'incident' database. Semantics yes, but in the world of legaleze it matters a lot I guess. The maps are all based on Google maps (as Waze is 100% owned by Google) but display differently and have a lot of user interactivity/input (think more of a community) so the information is often more up to date than more conventional nav systems such as TT or Google Maps.
Ultimately, it's free, so you have nothing to loose by trying it out.