DD6 is perfectly thrilled with her first grade class. The teacher is super excited that she's advanced and looking for ways to challenge her. So far the "challenges" are still too easy for her but it's at that sweet spot where it's not so easy that DD thinks it's for babies but not so hard that she can't spend most of her time chatting and socializing (which is what DD thinks school is about :>). I would say the math she's doing is at about a 2nd grade level, so just one level up, but since she doesn't mind I'm okay with that. Looking at my fellow parents, it's nice that I don't have to spend time helping her with homework or spelling words or anything.
I think this all will shift when she gets older and we'll need to make sure she's appropriately challenged, but it's fine for now. Also, things might change a bit when her teacher actually gets a look at her MAP scores (she still is"explaining" the harder homework to me as she sends it home, making sure I know how to help DD with it. So I don't think she realizes how easy things are for her.. probably because at school she spends more time talking than completing her work)