I travel by train quite a lot for work and have been looking for this kind of flask for some time - one that has all the qualities of a traditional flask but the convenience of an insulated mug.
It's solid stainless steel - very cool looking - but fairly lightweight. Drinks stay hot for a good few hours and crucially it is watertight so can sit on it's side in my workbag without soaking anything.
What I really like (and the critical deciding factor for me) is that once the top is unscrewed, you can sip coffee from it as you would with a cup. I wouldn't want to be pouring my coffee into a plastic cup whilst on a crowded commuter train and so the Drink Pod ticks all the boxes for me.
It has a great look to it, stylish and compact - fitting easily into my hand - and is no bigger than a compact umbrella so will slot into those side pockets of travel bags that are designed for small water bottles.
In terms of quantity, it holds 200ml, which doesn't sound a lot. In reality this is the amount you'd get in a large cup or small mug so it's not a massive reserve of a drink, but a bigger volume would need a bigger flask so it depends what you want. The convenience of a hot drink is worth the compromise and considering the £2+ you'd pay for a coffee at the station, this is a win-win for me.
I love it and enthusiastically recommend it to you.