I have blogged about Brooks Addiction 8 in previous posts https://drshoe.wordpress.com/2008/10/10/shoe-review-brooks-addiction-7-vs-8/ and have been waiting for the 9 to debut. Fortunately, the version changes have been worth the wait.
I much prefer the Addiction 9 to the 8 because it provides better midfoot fit. It also narrower which matches most feet better.
The toexbox depth of the Addiction 9 is shallower, so it won’t feel like you’re toes are swimming, which for some runners happened with the 8.
Other than these changes, the Addiction 9 is the same stable well designed work horse that the Addiction 8 was. Keep up the good work Brooks.