The major change here will be the loss of status earning on bonus points.
Really, that's one of the two major changes. That's the negative one.
The positive one is the change to calendar year. If you happen to have significant travel at varying times of year, the move to calendar year is a massive improvement. In the past, let's say you spent a month in hotels in April one year and in May the next year. Accor's status was worthless. Now, it'll stay around much longer. (Although sometimes the only "elite" benefit I've received has been a pathetic non-alcoholic welcome drink worth under a buck!) Given the same scenario, it would make sense for points to be valid until the end of the following year, not just status, otherwise we end up dumping points into airlines before they expire.