I haven't read anything by Cassandra Clare before but I know that she's most well known for The Mortal Instruments series. There were a lot of things mentioned in this First Impression that probably make more sense if you've read her other books already. I managed to follow along even with rapid fire introduction of new creatures and characters. The First Impression was just ok. I don't like YA paranormal/fantasy romance, so I probably won't enjoy this if the rest of the book is like the beginning.