Ok I just got my Seasonal Peach nailpolish in yesterday and to be honest, I'm really not all that impressed. I owned a few colors a couple of years ago that they don't make anymore and I remember the bottle being somewhat bigger. My bottle of Seasonal Peach looks smaller than I remember my other colors being.
I really loved the look of the nails on the model's hands as part of the CremeSheen promo picture on MACs site, it almost has a pearly look to them. However, Seasonal Peach in real life, doesn't do all that much for me and doesn't look all that similar to the picture on their site. It's a nude pink/peach, moreso pink. I put on one coat on my thumbnail yesterday and it streaked pretty bad, but that usually happens to me when I try and wear lighter/nude colors.
To be honest, no I don't think $11 is worth if for MACs nail polish, especially Seasonal Peach. I've seen similar colors for much cheaper.