I've really appreciated the vastly enhanced breadth and ease of use of the new dictionary.
I'm currently reading
Use of Weapons by Iain M. Banks and his usage of French cross over words would have left me a bit out-of-the-loop if it weren't for my Kindle 2's newly enhanced dictionary function. I've been enjoying the book far more than I would have otherwise.
The fact that Amazon currently has the Kindle edition of the title on sale for $1 helped my appreciation as well.

The title's content has me cracked up ROFL at times, I'm very much enjoying the tale.