I've long been a fan of the cheaper Thermocafe range of Thermos flasks, and regularly take one out on the hills and into work. They do seem to keep drinks hotter for longer than other brands of flask, and are lightweight and stylish too. Nonetheless, I recently managed to buy one that persistently leaked and dribbled, so was keen to replace it with one that was pretty much guaranteed not to. (Note that the leaky flask had the older style of pull-up nozzle, rather than the simpler twist-and-pour stopper that most newer ones seem to have. The pull-up nozzles were easier to use one-handed out on a cold windy mountain, but the twisty stoppers are much easier to wash, probably more hygienic, and do seem to be leak-proof.)
While this Ultimate Flask is flipping expensive in comparison to most, it really does keep your drink even hotter for even longer - almost too hot! It looks and feels like a premium item, and that lime-green band around the top is made of rubbery silicone, which helps prevent the flask from slipping out of your hand. (There's another silicone 'sock' on the base too, in black.) The twist-and-pour stopper seems to be of a slightly better design than those on the Thermocafe range, so pours particularly well. As for the cup, it's made from just one piece of moulded plastic - an improvement on the fussier plastic/metal combo style of cup, in my opinion. Last but not least, this flask does not leak or dribble.
All in all, I feel the Ultimate Flask is worth the extra money, particularly if - like me - you want to use it almost daily. This 0.8L size keeps me going with hot drinks all day. I've not tried it with cold drinks yet, but imagine it'll be just as good.