I've had a bit of an odyssey with thermos tumblers over the past few months. Initially, I tried the budget route since I thought, "it's just a tumbler, it should be pretty hard to go wrong". Realizing I had in fact made a mistake, I went for something a bit more expensive (more expensive than this tumbler), but was still left wanting both at the exorbitant prices a certain brand was charging for covered lids and from their mediocre thermal retention. Which finally brought me here to Zojirushi. Zojirushi is a somewhat well-known brand for rice cookers and other pressurized appliances, so it's only natural that they'd know what they're doing with a vacuum-seal and thermal applications. This thing is basically the holy grail of thermos tumblers. The heat retention is unbelievable. Compared to some of my other tumblers after (anecdotal) testing a couple of times, it regularly stayed ~20+ degrees F hotter than any of the others after being left to sit TWICE as long (the others lost their heat around ~2-3 hours, I gave up waiting on the Zojirushi to cool off after 6 HOURS). I'd go into more detail with some specific testing, but the difference between this tumbler and the others (vs. both a cheap $10 tumbler and a "premium" $35+$12 tumbler) was so drastic that I didn't really see the point. The lid is entirely leak-proof as new. I haven't had it very long, maybe after some wear and tear or being beaten around it might be possible for this to change, but I wouldn't count on it. The design of the lid has multiple gaskets and is enclosed, so there would need to be failure in multiple places for this thing to ever leak. You can try to force it to leak, turn it upside down, shake it around, throw it, whatever you want, but nothing is gonna come out. The lid has a lock for added protection against accidentally opening it in a bag or in some other bad situation. The cap on the lid is exactly what I'd been looking for, an enclosed opening that is covered completely when you're not drinking from it, but also opens enough that it won't get in your way while you drink it. It flips back fully and then locks in place so that you don't have a lid bumping against your nose. The opening itself is large enough for a good flow and also has a second opening for air to ensure a smooth pour. Again, the major plus here for me was that the lid is COMPLETELY sealed and covered. I'm not a fan of drinking from a lid out in public that I can't cover up or protect in some way, this solves that issue extremely well. The ONE thing that must be remembered about this thermos: As long as you take care of it, it will take care of you. You have to hand-wash it. It's not made to be put in the dishwasher or subjected to extreme heat or strong detergents. It's not made to be left soaking in hot water. It's not made to hold certain liquids for extended periods of time, like soups that are high in sodium since it can damage the interior coating. Assuming you use it regularly and always make sure to dump out any leftover coffee/tea/whatever then give it a rinse out it should last virtually forever. Take care of it like you would your stainless steel cooking utensils. Breaking down the lid is easy and simple. The parts of the cap come apart in a pretty self-explanatory manner, and it only takes a few seconds to run some hot water with soap and rinse it all off when you need to clean it. Some final considerations that I'd consider mostly subjective to each buyer: This 16oz version is pretty thin. Personally, this was appealing to me since it spends more time in a backpack side pocket than in a cup holder in a car. It's easier to carry and hold than some of the other, fatter tumblers I've had. There are other versions of this brand that are more or less identical, but are made to fit better in a cup holder. You can find them on Amazon and they cost the same price as this one. The closed lid is probably better suited to an active or on-the-go usage than someone that just wants to keep their coffee hot sitting at their desk. You could just leave it open, but one of the alternative versions with a different lid might be better if that's how you'd typically use it. I really like how it looks. It's simple, clean, and professional. No-nonsense kind of look, especially the stainless design. Some people might want something a little less "stiff" with extra designs. I haven't seen any Zojirushi tumblers that come in patterned designs or with anything like that, unfortunately. You could probably just get a wrap for it instead if you don't like any of the colors.