The search bar is more convenient, and sometimes the docs are hard to find. That said, I find a lot of docs are quite easy to read, and often have to take the second step of omitting SO or otherwise restricting the search to docs and kicking myself.
Some documentation is wonderful. I try to use documentation quality as an important consideration when choosing software.
The AWS docs have big issues, but they are similar to the big issues with SO - it's so easy to find old documentation. Also, they are horribly organized.
