I purchased this mug locally after too little research. The product suffers from serious design flaws. Despite hand-cleaning thoroughly after each use, the lid smells awful from old coffee and soured milk. There is liquid trapped inside the lid now, sucked into some internal chamber when I poured hot and then cold water over it in an attempt to kill the stench-causing bacterial colonies. The lid cannot be disassembled and can never be properly cleaned because of inaccessible internal surfaces. If that weren't enough, the click mechanism is showing signs that it's nearing the end of its useful life. All this after only a few months of use.

Another flaw is the permanent silicone sealing ring that forms a large lip inside the base between the polycarbonate middle section and the stainless bottom. This lip holds liquid even when turned or shaken upside down and is difficult to clean. Even after vigorously scrubbed with a plastic bristle brush, brown gunk comes off onto a drying cloth directed between the stainless part and the seal.

I think the "LiquiSeal" product line featuring this particular lid and base design is fatally flawed. This is sad because until it started stinking, it was exactly what I wanted: a well-constructed mug to keep liquids warm and truly sealed, pleasant to hold and drink from. That's why the mug merits two stars instead of one.

I've contacted Oxo to see if they have plans to fix these flaws, but the momentum of a large company is a tough nut to crack. A promising alternative that looks fully cleanable is the Thermos Nissan 14-Ounce Leak-Proof Insulated Travel Mug. My friend and unwitting guinea pig likes the one I bought him so far. I'll ask again in a few months.

OXO has really let me down this time...
I bought this cup about 2 years ago and for the first month or so, it was the best cup in the world. Didn't leak, kept hot things hot and cold things cold for hours and hours. Thought I found product utopia... then I kept getting sore throats and various infections. One day I looked at the lid and there under the rim of the lid is a pocket of sludge and slime, with no way to access it. I contacted OXO and I've yet to hear back from them. Terrible product...

First of all the cup works great and I fill it up and drink for about 2 hours and it is still very hot. I carry it in my ski jacket pocket and let it flop around in it without ONE drop being spilled. it works as intended and really this is what most people what to know about, not how very few people can't figure out how to clean a really simple cup.

Now on to my rant about the people that almost made me pass up a really great cup.

I bought this item even though I was afraid of the reviews that complained about the top getting gross. While I have only had this cup a short while I see what the problem could be with this cup and any problem can be handled by SIMPLY rising out the cup ASAP after using. Some of these people make it seem like the top is a super complicated mechanism when it really isn't!!

After using, empty remaining contents, click open top, rinse cup, rinse top while open, fill cup and put top on and shake out any leftover drink. Wash with soap at home. I have always done this with all my coffee cups and none of them are nasty before using the next time.

It is not that hard NOR rocket science.

I have to admit I take some people's reviews too seriously sometimes and have to wonder how some of these people get around in life.

Please don't think I am a neat freak, I am most certainly not. I just have the common sense to understand that leaving any flavored drink in a cup or dried in a top will leave you with a nasty mess to deal with later.
It is the same mentality of someone leaving milk to sour in a plastic cup, then lightly rising it and complaining the CUP is at fault for absorbing the rotten milk smell instead of the goof that left in there in the first place.

I think this tumbler is great if you're a tea or straight coffee drinker. If you have lattes and mochas every day, I think this may not be for you. Yes the seal is awesome, totally leakproof. The heat retention is great too, especially if you preheat.

BUT...it's true you can't really, truly clean the lid. If I were to drink anything very creamy, chocolatey, or (heaven forbid) with caramel, then it would definitely get stuck inside the lid seal mechanism.

Barring that, it's a great tumbler. Great attention to detail has clearly been paid in the design. The "drinking slope" of the lid was well thought-out; it's comfortable on the lips. The liquid has enough "travel time" out of the hole so as not to scald you. There's a rubber grip indentation, enough to be very comfortable and easy to hold.

One word of caution: don't submerge the lid to clean it. I submerged the lid in soapy water for a few hours in an attempt to clean inside the lid. This wasn't easy, since the lid floats. After I did that, a small amount of liquid became trapped inside and wouldn't come out no matter how I shook it, button up or down. I eventually had to make an even exchange for a new one. Now I never submerge the lid and I haven't had that problem since.

Bottom line: best for "clear" drinks. Don't drink anything thick or creamy, as it can get trapped inside the lid. The lid won't allow for full cleaning access, so rinse quickly after finishing your drink. I think if you can follow those rules, this is a great travel tumbler for you! Oh yeah!

I bought this mug on the recommendation of many people - and it IS easy to use and seems to be leak proof, but am thinking it will be hard to clean. The mug breaks down into to pieces, the lid and the mug, but there's no way to take the lid apart to really clean it. Just called the company to ask if I was missing something, but was told that no, the lid doesn't come apart, and they recommend washing it immediately after us, or at least rinsing out the lid when finished. Easy to say, harder for me to do - I tend to forget to clean it out right away and would have liked something that I could take apart and scrub when it gets gross.