I finished knitting this for Poppy last night. It's going to be one of her Christmas presents.
I have a weakness for vareigated yarn, and I really like the self patterning wool I've used for this. I've got enough left to make a matching hat too.
I got the pattern from this blog and it was really easy. I like that it is a unisex design. I think the sizing would be just right for 6-12 months. My yarn was aran weight and I used 5mm needles so that it would knit a little bigger. My daughter is a small 16 month old, it fits now and I think it will fit for a while yet.