WordPress 3.5 have many great tweaks but the one I really live is Media Section, it is so natural and seamless process of uploading, and adding new photos and images to the wordpress posts and pages.
After uploading you can click edit image link and this takes you to next screen where you can resize, crop or rotate image. What a wonderful time saver feature. You can now modify images right in WordPress to make them fit exactly in the area you want to use.
I am happily using this feature and find it great time saver when I need a quick fix to some image, no need to download, resize or crop in PhotoShop and then upload again back into WordPress. I am sure you will also love new MEDIA SECTION of WordPress 3.5, the latest version of this great open source blogging and online publishing software aka CMS .
Best Regards ,
Mohsin