Instruct: Classify Amazon reviews into positive or negative sentiment
Query: reliable bags

I bought these bags with the medulla pump in style. I found them very simple to use and have never had one leak. I don't understand why people complain that they do not stand up. Why do they need to stand up? After defrosting you transfer them to a bottle anyway. I have never been able to get one to tear (for pouring ) but I just use scissors. And the twist tie feature is as simple as tying up your bread bag.