These are really comfortable and it does actually feel like you are going out in your slippers. I would advise a smaller size though as the fit is slightly large. I would have been better to get a size smaller.
I really like this. I bought it to replace a Kenwood smoothie2go which has gone up in price massively since I bought that. Having had the on/off switch break off on the Kenwood s2g, I'm impressed this is activated by pushing down on the bottle. I think the larger cups on the Kenwood are better to drink from, but these bottles are a bit more portable to take to work etc. Overall a good purchase.