I almost didn't buy this Contigo mug. My previous Contigo West Loop autoseal mug developed a funky mold in the lid from creamer getting trapped in the complex closing mechanism (I'm not someone who lets dirty dishes sit. I washed/rinsed the mug everyday but I obviously wasn't getting the lid properly cleaned. It was so nasty. I've included a picture so you can see for yourself all of the places that need to be cleaned on the West Loop versus the simplicity of the Byron lid.) After my Contigo failure, I went with a Thermos brand hydration bottle, but then it voluntarily opened its lid on its own all throughout my bag... the bag containing my (now-dead) MacBook.Back to the drawing board for a new mug for me because I don't trust the Thermos, and no more putting my coffee mug into my laptop bag. I looked closely at this Byron mug before I bought it and saw that the company redesigned their lids. Thankfully, you can get at all the parts to clean this Byron snap seal's improved lid.The difference between this Byron model and the West Loop autoseal model is that you have to constantly push the button in while drinking the West Loop model, making it spill proof. This Byron mug has a thing you flip to drink and then flip back to close it. It definitely takes some force to open it. I can't get the lid to open/close unless it's on the mug and my hands can't be wet. Another difference versus the West Loop versus the Byron is that the Byron stays open till you close it. For clumsy folks, this Byron mug may not be your best bet. You can tip your mug over while the lid is open and make a mess - ask me how I know ;) On the plus side, since this Byron one is so tight, I've never had this it open itself on its own on me like a Thermos one did.These Contigo mugs should be hand washed (the lids not soaked for a long time) and rinsed really well. On my previous Contigo lid, it absorbed the taste of dish detergent not too long after I got it because I soaked it too long in the soap. Yuck, yuck, yuck. That was a terrible surprise to start my workday one day. I had to work to get the soap taste eliminated - took a lot of soaking in baking soda to get it gone. Although it says you can, I wouldn't advise putting the lids in the dishwasher because it may develop a funky taste from your detergent. Also don't put the bottle itself in - if you buy a colored one, the paint will come off the outside in the dishwasher. Even though I hand wash, I chose to go with the gunmetal so if I banged this mug into things (ok, when I bang this mug into things), it won't have spots where the color is removed.This mug keeps drinks scalding hot for a half hour or so and very warm for hours. If you want to drink right from the mug relatively soon after filling it, I'd advise leaving the lid off of it for a few minutes after you make it. It stays cold even longer than things stay hot, and doesn't leave sweat rings. To make the hot or cold last for even longer, you can preheat or precool the mug by placing boiling water or ice cold water in and letting sit a few minutes before adding your beverage.All in all, I'm very happy with this new improved mug. There are pros and cons to the Byron versus West Loop but I'd rather be sure I'm drinking out of a clean lid with the Byron and remember to close my lid when I'm not taking a sip.