First let me say that I loved the first book. I've read it like 5 times and I was so excited to get the next one... yet after reading I'm not so excited anymore. The book had potential to be good. Haruhi's antics never fail to amuse, and I love the characters, but lately Kyon's dry sarcasm has been getting a little whiny. No one is forcing you to be in the SOS Brigade. If you can't stand what Haruhi does, LEAVE! Honestly....
No, the main problem with this book is that the whole thing is basically Kyon obsessing over Mikuru. In the first book it was sweet, because she was new and he had never been around so many beautiful girls before. But in this book, it's annoying. And for a time traveler sent to observe Haruhi, she's kind of a wimp. In this book, Kyon spends most of his time describing Mikuru, and obsessing over her. LOOK, WE KNOW SHE'S CUTE, GET ON WITH THE BOOK!!!!
I have to say I am shocked that someone who wrote the first book, which was wonderful, could write this snore. I can honestly say that if I hadn't watched the anime, I would not bother to read the next one.