While I enjoyed this book immensely, I wouldn't recommend it as an entree into the Vorkosigan series - I think you need to already know and love the characters.
It's not slow-moving, really - but not much happens. It's a romance/soap opera, more than the action-adventure that most of the series could be classified as.
The story is nearly wholly involved with Miles' bumbling attempts to woo the widow Ekaterin, and the social comedy/drama that follows upon that.