Whilst I have only had 2 cuppas in this thing, I certainly can tell you it's great! You can make the brew in the mug (Unlike some other travel mugs with necks as seemingly small as a golf ball) without any issues in getting the teabag out, and it's, in my experience, 100% leak-proof. At 20 quid, it might seem like quite an investment, but the cost of getting a cup of standard tea on one train company in the UK every weekday morning will repay this mug in around 1 and a half months. It keeps drinks hot for a surprisingly long time (I have left this mug for around 3 hours and it's still tongue-tinglingly hot. I haven't tried it with cold liquid, and so cannot vouch for anything there. The outside of the bottle is cold to the touch (Unlike the liquid within!) but if your looking for something to keep your mitts toasty, the lid stays quite warm. In conclusion, a solidly build mug, leak-proof and keeps thing hot for hours. The lid is a bit of a pain to clean (It is dishwasher safe, but needs a rinse through which seems more like an advanced voodoo ritual before throwing it in) and unless you get the silver colored one (This is clearly not) the actual cup has to be hand washed. The price is also quite high. This mug scores 4 stars from me.