I certainly was. It was the first book I've read from her and was pleasantly surprised by it; I like her style!
Have also read "undomestic goddess" shortly after "Can you keep a secret" and liked it just as much and am now waiting for the first part of the Shopaholic series to arrive, ordered it on Ebay yesterday. Parts 2 - 4 are already waiting in my bookshelf, got them on a German book exchange site, and I'm now looking forward to finally start reading them.
By the way, did you know that Sophie Kinsella is also writing under her real name Madeleine Wickham? Haven't read any of those books though.