Eventual consistency is easier to implement but a pain in the butt to use. I shy away from SimpleDB for that reason alone - it's too hard to wrap my head around it.
SimpleDB is hard to get from a traditional SQL point of view, but it's a joy to use in practice. My simple-minded solution was to add an invisible local cache for all of my writes and except the fact from all other players that I'm possibly reading an outdated data.
Eventual consistency is pretty close to real life situations, just try to image the overplayed "bank account example" in a real life bank around 1900 with all manual account handling.
It's not easier to implement. You actually have to go to a lot of trouble to build in sideband data that can be used to establish causality in the system. And everywhere your data passes through needs to be able to handle multiple divergent versions and reconcile machine quorums.
