I wanted this because One Green Bottle in the UK don't do curved ones any longer, and I find them much easier to hold than the straight ones, as I have co-ordination issues (due to being autistic). I am mostly happy with it, and the choice of sizes. And the OGB lids fit, which is good, as I don't like the type of lids they came with (they're larger, and prone to snapping when you drop them).
However there is a seam at the bottom of the bottle (which OGB doesn't have in theirs; they're smooth), which I am concerned will accumulate dirt and bacteria and make it hard to clean (and need cleaning more often).
Also although I met the criteria for a free bottle as I bought two, I didn't take it as it would have increased the postage price. So not actually free then! I didn't need it anyway though, so it would just have been a waste of resources (though I could have given it to someone who doesn't have one yet).
