At first glance, it looks cute, but there are some problems.
For one thing, I miscalculated about where the top of the shoulder should hit on the side with the button-on shoulder, so the sleeve is sort of shifted compared to the other sleeve.
For another thing, it just doesn't look even in several ways. If you eye the single-crocheted collar, you'll see the line of knitting underneath looks significantly different on the left and right sides, though I did try to do matching decreases.
And finally, what you can't see: the seams are a bit bulky for a baby (this is a problem with virtually all handknits for babies, though) plus the cloth didn't come out as soft as advertised. It is drapey, though — would make a great adult woman's top. But for a baby, next to the skin, it's OK, but not as fab as I'd hoped. That would be okay but this is a T-shirt, not a sweater, so those seams might itch.
So this is going to marinate in the FO bag for a while, and I'll think about what to do with it. This yarn is really not reusable after you rip it, so hopefully it'll be wearable.
Meanwhile, I have enough Katia Irina left for a second baby's top. I think this time I'll do a henley-buttoned, top-down raglan; that'll take care of the seam problem, and make it more actually wearable.