2 stars because director failed to show how come sally forgot about all the event if she was in time loop. Also you cannot make anyone kill. Even if i was in her place i would have never killed them, at all. Also It took her complete time or what so ever to realize that everything was repeating.
(She was wearing same clothes, she was disturbed, shows she was in loop already since beginning) so she knew all the things so why didn't she say anything. May be she was in shock but it was not first time it was like 20 times it had repeated...
Great plot but could have been better if it could have been shown that how time loop came into existence and may be it could have stared much much later. i.e after several familiars of her to save them like 4 or 5 ways she tried and then some note revealing how to break this time loop stuff !