I would have to say that I give this book 3.5/5 stars. I have the same issues with this book as I did with the first two in the series. The book starts out really fast paced and ends in a flurry of action. The problem is that all of this action at the start and the finish comes at a price in the middle. The book is so slow through the middle that it is almost unbearable.
I appreciate good character and world development as much as any reader does, but there comes a point when you go too far with it. Paolini reaches that point and perhaps goes over it. I'm not an author, far from it in fact, but I feel like he could have accomplished the same effect he got with about 100-200 less pages. Don't get me wrong, it's a great story but it takes him too long to tell it.
I will get off of my soapbox now. He does a great job of storytelling at the end and completely makes up for the dragging through the middle. So, I will get the 4th book when it comes out. As far as I know he hasn't set a release date yet for the last book. I hope it's not too far off because I don't want to have to read through all of these books again to remember what happened and why. I guess we'll just have to see how it goes.