Addie I read the books in order, but the first one was always my least favorite. I am reading the second one for the third time, and don't need the first one to remember whats going on.
Francesca I enjoyed the book without reading the first, but, if you read the first in the series, you will understand some of the minor characters better (specifically Rosalind). All three books in the series play off of each other, but any can be enjoyed without reading the other two. If you can't get a hold of Dragon's Keep, Dragonswood is still a great read, but it would be better if you read the first book first.