Kendra Little has a webcast + transcript covering isolation levels when dealing with In-Memory OLTP:
Whatever you’re testing, and I really think this is an exciting area of SQL Server to say, “hey could I engineer something really fast with this?” Whatever you’re testing, the isolation levels here can be confusing, because this is really different than disk based rowstore tables in SQL Server and disk based columnstore in SQL Server, as well.
It’s not bad, and I think once you start playing with it it isn’t even hard with the In-Memory OLTP isolation levels. In part, because there’s only three isolation levels! There’s actually fewer isolation levels, and once you get used to how they work, I think it makes sense.
But it is really different, it’s definitely worth playing around with.
I’d really like to see Read Committed isolation become available for In-Memory OLTP someday, but in the meantime, Kendra does a good job walking through the isolation levels which actually exist.