Saw Hard Candy a few months ago when it was in theatres here (Ellen Page is a Haligonian!). Pretty good... but uncomfortable. Very uncomfortable. I had to grab my testicles a couple of times just to make sure they hadn't imploded.
Haven't seen SD yet, but I'd really like to. Seems that one has been in post-production for years. My father had told me all about the book and the premise is interesting (although more original for its time compared to the type of movies Phil Dick's books have inspired). Plus I really like Linklater and the advanced rotoscoping technique used here is a huge jump over the interesting, albiet intentionally rough-looking and low budger, Waking Life.