I was initially pleased with this, even though the lid of the drinking spout comes undone rather easily. In summer I mainly drink cold-brewed teas so for the first few months I was ok, however the first time I brewed a hot drink (which wasn't boiling - it was a green tea brewed at 60°) I found that the lid all of a sudden was leaking. On further inspection I found it didn't fit on properly... As soon as I emptied it and the glass was cooled down it fitted fine again & no leaks. I then tried again with another hot drink, and again got the lid not fitting & thus leaking. I assume that as it heats up the glass expands enough to affect the lid not fitting snugly, so I cannot use it for hot drinks. Maybe I got a bad batch, but unfortunately noticed too late for me to return.