So far we're pretty underwhelmed. He's happy enough socially - fits well with the girls and not so well with the boys (he likes playing tag and using the play equipment, not pretending to shoot each other or duelling beyblades). Academically he's still a mile ahead of his classmates in most areas, so there's really been no challenge yet, and the things he's met that he's never learnt before (what an adjective is, for example) he's learnt, mastered, applied, and moved on with while the other kids are still reviewing it.
The only real 'benefit' I've seen so far is that he's decided it's ok to write, and has been doing so on a daily basis - stories, non-fiction, all sorts. It's like he looked around and said, hey, I can do that too, and off he went.
I'm not sure where to next with it really, I know they'll suggest more hours soon (it's end of term this week, so I expect they'll want him another day next term) but if this is all they can do for him, I can't see it working. On the other hand, if he's there more they might spend some more time meeting needs instead of slotting him in to what's already happening.
The busy work and the waiting around is driving both of us a little mad though.