My first session of 4th graders used Code Combat on the first day, and they loved it.
I was thinking about using Code Combat through my whole session, as a way to introduce programming, because the kids loved the site so much.
But, there are issues.
* The browser loses focus. Kids don't touch type so they don't notice this until they have been typing for a few minutes sometimes(?!)
* Finding typos is incredibly frustrating for these kids. Javascript has a lot of "syntactical overhead" that gets in the way of learning core concepts.
* They just get stuck and need someone to help them. At the elementary school age level, they have about 5 minutes of total patience before they stop. They don't "rage quit" like middle school kids would, they just start goofing around.
I think these are resolvable issues, and I actually think the Olark idea is a fairly good one.
In the end, I ended up using MIT Scratch to teach most of the class. It got rid of the syntactical issues, and lets them express their creativity visually and with sounds as well.
It has its own set of issues too though since it's a visual language and some things are just hard.
That said, I'm still excited about Code Combat and watching developments closely. Keep it up guys! All the kids want to keep coding so maybe I'll try again in January!
FYI - Here's more info about that particular class: http://douglastarr.com/coding-class-week-1/