It's both heavy and fragile. I don't trust plastic to drink out of habitually, but there's virtually no risk to expected from short term use of food-grade plastic and it's much more practical in difficult situations.

Plastic also has the advantage that you can use it to sterilize water. Glass blocks too much UV, but a couple of days in the sun will disinfect water in a clear plastic container. You can have safe water indefinitely just by rotating containers (at least here in the Pacific Northwet, where availability of some kind of fresh water is more or less assured).