I'm have no experience with Citizen Eco-drive. But if I'm not mistaken, it's an advance dive watch, not a dive computer.
All divers watch have this basic similar feat, 60mins rotating bezel. Although we have many diver watch lover around, not everybody knows how to properly use the rotating bezel. For a serious diver, this rotating bezel is a serious thing when you want to determine the safest time for a diver to be at CERTAIN depth. U have to calculate it by using a dive table a.k.a RDP and use the watch as a tool to 'remind' u of the time. However, dive watches are the last thing u would opt to if u were to use it for diving. Long ago, dive comp are scarce and expensive. So, the most practical, people use a dive watch (very popular Submariner at this time)
In modern time, we have dive computer to help. People dive for many reason and most - for fun. Having to calculate and recalculate for each dive is no fun. It is also less practical because sometimes u want to go deeper or shallower depending on what u gonna do underwater. Therefore, dive comp helps a lot. It calculates at real timing the safest depth, the safest time, it notify safety stop or deep stop if needed and it will calculate ur minimum surface interval or us will risk herself to DCS.
SERIOUS diver, go for dive comp. One interesting thing, I've yet to see any diver brings any expensive dive watches for diving. Most is the famous sskx007/009 and that's very very seldom. Same goes with having a 500m/300m/200m/100m dive watch. We just appreciate the technicality and the complexity demonstrated by the watch.