I'm not fond of the AddBooks page...and then having to choose book, wait for the update and then edit book...I'd much rather search for a book and add then edit the book from the book's main page. I like to look at the tags on the book's main page before I add my own tags so the quick edit tags field is useless to me.
I'm a bit confused about Groups. I have not used Groups much yet...I have used this feature for the EarlyReviewers program and 50 Book Challenge but I'm not sure how you get updates and emails from groups or if you need to officially "join" a group in some way to get emails from group posts (as per GoodReads). Its a whole can of worms I do not want to open and time, brain power I'm not yet ready to expend.
I wish I could see my whole review when I edit a book rather than having to scroll through the box...sometimes I delete text I did not mean to...I preferred it the way it was. That's all my gripes!!! But I love the look of the site now and I always look forward to reading the State of the Thing Newsletter.