I used to have a plastic Cirkul when they first came out, and I was very intrigued by the concept of it, but I ended up using it maybe a handful of times before it spent a long while sitting in my cabinet until I gave it to a friend. This new metal design is SUCH a major improvement for Cirkul! My water stays cold through most of the day, and then my ice is still there the next morning for me to put more water in. I love the look and feel of the bottle as well as its effectiveness in keeping water cold for long periods of time. I've only had this new bottle for about 2 weeks, and I've already used it waaay more than I used the original plastic Cirkul I had for close to 2 years. I'm really enjoying trying the different flavored cartridges, but of the many we've already purchased, I keep going back to White Cherry and my husband LOVES the lemonade and sweet tea flavors. Such a great investment, and we've been drinking more water in the past couple weeks than we normally would have in a couple months, if I'm being honest. Such a great product, quality made, helpful when you tend to stray away from drinking water, and so many different flavor options to choose from all while staying at zero calories and having encouragement to avoid sugary drinks. Amazing. We've already been buying cartridges frequently, but I can definitely see us buying more bottles to keep at the office as work Cirkuls.