Just upgraded my local install as a test before my main site.
Everything seems fine apart from 2 things.
I use the Lightbox Plus and easyest gallery plugins (and woocommerce) on a very image heavy graphics website and after upgrading any galleries (lovely inplementation btw) on new posts don't work with my lightbox although single images do. Instead when clicking on an image I am taken to a page with the image embedded with a link at the bottom for full size image. Upon clicking on the image it loads a page with the next gallery image also embedded.
Not sure if it is lightbox plus (I have the use for galleries ticked) or some setting for galleries in 3.5 that I can't find?
My other problem is the count per day plugin throwing errors on it's admin page. "Missing argument 2 for wpdb::prepare(), called in D:\Program Files (x86)\Ampps\www\wp-content\plugins\count-per-day\counter-core.php on line 217 and defined in D:\Program Files (x86)\Ampps\www\wp-includes\wp-db.php on line 990"