About 6 years ago, I started using basic stainless insulated thermoses and became a big fan because they kept my drinks warm OR cold, and liked that there was no external condensation. HOWEVER, I threw them out over time because the taste of my beer, tea, coffee, etc., had changed, as I could tell there was a metal taste present.
BUT now I have met the perfect insulated mug. The ceramic coating on this tumbler does make a huge difference. It keeps my drinks cold and warm for a ridiculously long time (with no condensation), and I can taste my drinks as they should taste. I cannot live without my daily tumbler, it goes with me to the office and back.