I have Pyrex that's 30+ years old, and some I bought last summer, and probably use a piece of it 7 or 8 times a week. I have a couple basic rules: don't put it from freezer to hot oven, don't put it hot w/ hot food into fridge or freezer - allow it to cool a little. If you bang it against something when you're handling it, inspect it very carefully for tiny cracks - I've read that pieces w/ any degree of cracking are more likely to explode.

Also, I would avoid pouring very hot liquid into a piece just out of the fridge or freezer, but if you're mixing room temperature ingredients in a room temp container and pouring in boiling water, I would not expect problems.