Not to older devices it doesn't. Lumia Denim doesn't appear to change much in older devices, naturally.
If your opinion is that below is not much then indeed it there was no change.
•Welcome the all new Glance Screen with more information from apps like Bing Weather or Bing Health and Fitness. The new Glance will now show Date info too. Details like Time and Notifications are already present.
New features from the Windows Phone 8.1 Update 1 (officially called Windows Phone 8.1 Update)
•Folders. Folders let you organize your Start screen the way you want. Just push one Tile on top of another one to create a folder and get going.
•Messaging. Combine multiple text messages into one, and then forward them to someone else.
•Selection. With improved selection, you can now delete multiple calls, messages, or contacts.
•Apps Corner. Apps Corner lets you specify apps other people can use on a Windows Phone. Great for individuals and any-sized organizations who want to provide only the essential apps for others to use for work, school, or any other reason.
•Cortana. There’s another way to start Cortana from a Bluetooth hands-free system in your car now—just tap the contact named “Cortana” and ask her whatever you want. And now you’re able to do more things without unlocking your phone too, making your personal assistant even better.
•Internet Explorer. Improvements to Internet Explorer 11 for Windows Phone give you a better browsing experience on your phone. Spend less time panning and zooming and more time enjoying some of your favorite websites.
•Alarms. Now you can customize the snooze time for an alarm, and then enjoy a little more shuteye for the time you want.
•Accessory apps. Use accessory apps to get notifications from your phone on your smart watch, active phone cover, fitness tracker, or other kinds of accessories.
•Internet sharing. Now you can share your cellular data connection over Bluetooth, so you can get an Internet connection on more kinds of devices.
•VPN. VPN now supports L2TP, which lets you connect to more VPN services. Whether you connect to a VPN for work or personal use, you can do it on your Windows Phone.
•Narrator. Narrator now has touch typing and a way for you to turn off hints for controls and buttons if you don’t want them read aloud. Some other improvements to Narrator help you unlock your phone a little more quickly, find and use the Back, Start, and Search buttons more easily, and tell you when your phone screen is on or off.
-Cellular data toggle in notification.
-Battery saver as live tile.