I agree with your post completely except for the importance of speed. I would rate documentation above speed in my evaluation of an api. If its not documented

I agree with your post completely except for the importance of speed. I would rate documentation above speed in my evaluation of an api. If its not documented I can't use it, regardless of how fast if is - if its documented badly and I can't easily use it, I quickly move on to an alternate offering. Fast is great, and important, and nice to have, but documentation is a deal breaker. I could go further and say that docs are even more important than "it works" because without docs my definition of "works" may be different to the authors intent.