Disappointed with one ui 9 beta

You will definitely get 7 years of Android updates. However, as has been the case for years, many of the newer features, ie bells and whistles, will not be pushed down to older devices.

Eventually, most of the features trickle down to the older devices, usually, with later beta builds or sometime after the official release. If the feature is not limited by hardware constraints, which most are not, then we should get it.
Now Brief and Audio Eraser come to mind. These did not trickle down for quite some time but eventually they did.

Per Google Gemini here is the feature list for the S25 and S26U. Time will tell how many of these the 24U gets.

Samsung’s One UI 9 beta update, built on Android 17, introduces a sweeping set of features focused on deep personalization, advanced Galaxy AI tools, refined UI animations, and improved efficiency.

The top features included in the One UI 9 beta updates span several major categories:

⚙️ Quick Panel & Interface Changes

Redesigned Media Player: Features a fluid wave animation during music playback. Tapping the "now bar" expands the album art seamlessly across the home screen.

Independent Controls: Volume, brightness, and sound profiles can now be toggled and resized independently to optimize one-handed control.

Faster Tile Navigation: Tapping certain quick panel tiles (like Comfort View) expands them directly into full settings pages rather than dismissing the panel first.

Sleeker Lock Screen & Visuals: Features a subtle glow on lock screen waves, simplified settings descriptions, and larger, cleaner categories inside the My Files app.

🤖 Galaxy AI & App Enhancements

My Fan Cam: An AI-powered camera feature that automatically tracks and follows a selected person while recording, reframing the video for different aspect ratios.

Smarter Now Brief & Now Nudge: Re-engineered to provide highly context-based suggestions and customizable info cards tied directly to your daily routine.

Samsung Notes Tools: Adds creative features like a decorative "tape" tool (with hidden/unhidden options) and an expanded list of pen line styles.

Creative Studio Profile Cards: The Contacts app integrates directly with Creative Studio, letting you design stylized, AI-prompted look cards for contacts during incoming calls.

🔋 Battery & Performance Optimization

Granular Display Refresh Rates: Introduces new intermediate LTPO refresh rate steps (20Hz, 26.67Hz, and 40Hz) for compatible flagships. This allows the screen to drop power consumption precisely when displaying static elements, improving overall battery endurance.

🛡️ Security, Privacy & Control

App-Specific Internet Restrictions: Users can now block internet access for specific apps (e.g., keeping WhatsApp offline while staying online on other apps).

Location Transparency: A distinct blue indicator now explicitly flags when an app is accessing your location in real time.

Suspicious App Blocking: Enhanced security protocols auto-detect high-risk apps, blocking installation/execution while explicitly recommending their deletion.

Warranty & Care Menu: A new centralized diagnostic section under settings allows you to run full device diagnostics, check warranty statuses, and initiate remote support.

♿ Accessibility Upgrades

Text Spotlight: Displays any selected text in a larger, highly legible floating window to reduce eye strain.

Combined TalkBack: Merges Google's and Samsung's individual screen-reading packages into a single, unified service.

Enhanced Mouse Control: Replaces awkward swipe gestures with a single-tap select and introduces customizable Mouse Key cursor speeds.

The beta program has been steadily maturing ahead of its stable rollout across older flagships like the Galaxy S26 and S25 series.