From an online Chat Here are the changes

Notification tweaks
Free Preview display changes
On-screen keyboard enhancements
Tuner customizations for HDPVR 630 users

Reorganized Preferences Menu
The Preferences Menu has been reorganized and new headers have been added to further break down the customizations that can be made. Any previously customized preferences may have moved locations, but the setting will stay the same.

Notification Display
Based on customer feedback, 50.25 allows users to choose what types of on-screen notifications are displayed, based on three different levels. Note, most alerts such as dual recordings, auto-tune and reminders are not affected and will always be displayed.

Alert Advance Notice
Users can adjust the amount of time before an on-screen Alert (such as dual recordings or auto-tunes) appears – from as little as 30 seconds, up to 5 minutes. The default value is 2 minutes.

Free Preview Display
Channels that are on Free Preview now have gold channel numbers and a gold treatment around the Channel Cell in the Guide. When you tune to a channel on Free Preview, a new banner will appear indicating the Free Preview status.

On-Screen Keyboard
We have introduced an easier way to input letters into on-screen keyboards (Keyword Search or User Name entry), with alphabetical entry using the number pad on the remote. For example, press 2 three times to get to the letter C, followed by ENTER.
We also have new shortcuts for Delete (RWD), Space (FF) and Clear (SKIP BACK).

Release Notes
We have added “Release Notes” to the Status Menu Bar so that users can see what has changed in a particular software release, after they’ve dismissed the initial Welcome Screen. This has been added as direct result of customer feedback.