Pros
Wrote an entire book outline, which was good practice
But they still haven't paid me for it, so...
Cons
Just the most hypocritical, mismanaged thing ever. It takes them weeks to respond to your messages, but they expect you to respond to them within hours, no matter your time zone. They have no idea how to prep you for working for them--they give you multiple sets of rules that all contradict themselves in later email attachments. They only give critiques, never affirmation. You're expected to be the content creator, editor, and format coder for the entire game. They only critique your work, never affirm it. I'm sure they do this from the start to make sure their writers undervalue themselves.
They refuse to answer any questions, but will send you aggressive emails later with the answers once you've already submitted drafts--i.e., Why didn't you use this other file format, when you had already asked them which file format you needed to use but they had never responded....
I could go on.
I know you want writing experience and the pay rate doesn't seem totally horrible, but I can promise you it's misleading. They pay you very little for hours of extra fruitless labor, only mentioned once you're already writing, and the most irritating part was--they aren't real editors! I had to edit THEIR edits, for grammar and spelling mistakes they would ADD to my drafts.
You can do better.