I love the "sets" (Birthday set / Slumber party set), they're such a fun way to give a kid a wide selection of ponies / gimmicks.
That said, I wish it had five DIFFERENT types of ponies instead of two newborn twins. I get that Newborn Twins were one of the sets that year, but Big Brother ponies, Princess ponies, Pony Friends (the animal pals), and Sea Sparkle Baby Sea ponies (the ones with painted on necklaces) were also sets that year, and I'd rather have seen any two of those instead of the Newborn Twins. Just for more variety.