I have one and like it - it keeps my baby warm and cozy. I haven't had problems w/ it riding up at all. I swaddle often even with the bag though to prevent my baby from waking up when he moves his arms but even when I don't swaddle, he sleeps well in it.
My son (~4 months) loves them - he didn't love swaddling and refused swaddling after 4 weeks, so the sleepbags are perfect. And he's been in the same ones since they aren't sized, so we have gotten many months use.
Re: Sleepbag?
We have three of them, size 0-9 months, and DS outgrew them before we got much use out of them. The arms are rather tight.
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