I just uploaded a bunch of files to Amazon S3. From the point of view of the actual service, I have no complaints so far. From the point of view of the user experience, however... the situation is appalling.
Not having a standard SDK for the major platform is stupid. Yes, you have SOAP / REST api, so what? I am not going to deal with them. I don't really want to. I want an API that I can use from the get go.
At the very least, you should have someplace where you list the community contributed API. By language and platform.
Right now trying to find an appropriate API is a horrible experience.Especially since most of the API on the site seems to be sample code only, not fit for real use.
By that same token, not having at least a web GUI for my items there is another problem. I had to go through several client programs before I could find something that even semi worked.
Again, the service might be good, but the user experience is really detrimental.