To start theres alot going on in the update. Excellent interface and great integration of the stats plugin, displaying of comments and the ease of which changing and adding content can be manipulated, from the front dashboard is top draw. Installation was as easy as ever so don't hesitate to add the update its worth it in the end. One major change is the adding of media on your post page and support for adding content fast and easy with simplicity. The main aspect of the 2.5 update is CONTROL and the ease of it especially the tags control and media library. I'm still playing around and picking up on the way it works.
One thing I noticed were the widgets, it has some improvement but if you have a 3 column blog moving your widgets from the left to right columns is a bit of a pain. In the past, you could do this by moving it on the fly from one to the other, and from one side to the other side. This isn't available in this update and the widget columns are contained in separate windows and not displayed together. Ive sorted it by saving the text widgets ...