This works well. I have the speed and cadence sensor in addition. It is indeed a net Evolution over conventional meter, you can vary the displays, be guided ... However, for the wattage it is mandatory an energy sensor, because the garmin offers no estimate watt, based on cadence, speed, road type, slope, that garmin could still do because they have the database and they could provide estimates based on their stats harvested. The power meter generally costs more than 1000, so it's a shame not even have an estimate of watts, for the price of the product. Sigma rox offers an estimate of watts for example.
The cards are overpriced and basic gis has no bike suited cards because only the main roads. I have no moral concern to téléchaargé maps torrent for once, because the Garmin maps are too expensive.
summary: Compared to the screen of a smartphone or Google maps, it's still grim but in action, on the bike, it works well and is ergonomic. I am disappointed not to have to estimate watts, and the cards are expensive but I'm satisfied with the purchase.