I usually recommend to my friends that they read this series in publication order. There are some strands of storyline that do not follow on directly from each other, however once you get immersed in the books (and you will!) the chronological order of events doesn't seem to matter. You just want to find out what mayhem Miles is going to cause next!
I prefer to follow along with what the author was most interested in exploring as she developed the series. If that means jumping back in time a little to back-fill some context or history, then that suits me just fine. I started reading the Vorkosigan Saga in the early 90s and have spent plenty of time waiting for each of the books to come out, so that may influence my preference for publication order.
I think you'll really enjoy this series, no matter which order you decide to read them in.