Well, from the name of this product, you’d really think it’s a monster, but this mug is almost regular-sized. Just a little bit squat. Or should I say Sas-squat? :)This will be a long review, so you may as well get yourself a cuppa."Double-wall vacuum insulation keeps cold drinks cold and hot drinks hot until the last sip" is how the product is described, and it doesn't fully live up to that promise. Still, I think this mug is worth buying.The first time I used this mug, my coffee stayed hot for about twenty minutes, warm for another fifteen or so, and just tepid thereafter. I’m not sure why other reviewers say their coffee stays warm for hours, but perhaps they ordered the separate lid that closes completely. The one that came with this mug is the kind that is just an open slit, so it’s not as effective at keeping heat in.The tiny tab makes it slightly difficult to pull off the lid, and there is a vacuum seal, so if you do it with a full cup of coffee or tea, set it down on a hard surface for leverage so it doesn’t spill on you. Since the sides are smooth, there’s no traction for your hands.The second time I used it, I ran the empty mug and lid under hot water before adding my heated coffee to it and it did stay warmer, longer. No matter what, though, with this model, the heat will dissipate through the slit opening. By the third try, I ran the mug and lid under hot water, put the heated coffee in, and also put a make-shift covering over the slit opening. It helped somewhat, but I still needed to re-heat after an hour or so. The covering I used was a napkin, weighted down by a round fridge magnet.Despite its shortcomings, I’m still a believer. It does save me from having to re-heat in the microwave as often. I’m a slow sipper, and since I add creamer to my coffee, I’ll inevitably end up with that dreaded layer of burnt-creamer film across the top of it which has to be scooped off. This is a nice, solid mug and the handle is comfortable enough, although it’s not padded. It’s not spill-proof due to the slit opening, so I wouldn’t recommend taking it with you in your car. Also, I doubt the wider bottom would fit into any standard cup holder.Another minor issue is that condensation forms underneath the lid which may dilute your coffee.In closing, I do recommend this mug, but if it’s imperative that your cuppa stay piping hot, consider the magnetic slider lid version. Told you this would be a long review! Thanks for listening.PS Just a reminder not to put this mug into the microwave, as its inside is made of stainless steel. It’s easy to forget that it’s not microwave-safe, since the outside is a seafoam color with just a hint of silver across the top, making it look like a regular mug. The reminder not to put it into the microwave is on the inside of the label in small print, so you may miss it.Update on 2-7-19I'm not as bullish on this mug after using it for almost a month due to the difficulty of opening the mug once condensation from coffee steam forms a vacuum seal. I'm not sure keeping your coffee slightly warmer for a little bit longer is worth the hassle of having to fight with your mug to get it open. Coffee break or tea time is supposed to be peaceful!