First, what is the update and what is it not? The update covers the Steam library, listing the user’s games and the display of individual games themselves. It’s not a revamp of all the web pages and application views that form parts of the library, like achievement pages or the downloads view. Those will likely be updated in look and feel to match the new styles over time.
The biggest change is the addition of the new home section, which is a jumping-off point to other parts of the library. It adds a new events/news serial at the top, where you can see game news including media and updates to games.
The primary art for games is now in portrait format (600×900). This, alongside the addition of a large banner image at the top of each game page, are the biggest visual changes. The portrait format affords space for text and art with some separation where the old banner style (what Valve calls capsule) really require putting the two together. But the capsule format is still used in at least a few places, including for the most-recently played game and on the downloads view.
The collections system, formerly more like tags, now allows for dynamic grouping. I tend to track several properties of games, like whether I played them yet and what their style of game is, besides noting of they require a EULA or have broken features on Linux (a few games I’ve played required using Proton in order for achievements to unlock).
One downside of the collection system is that if you navigate to a game from the home screen, it will be opened from the first collection alphabetically. It might be useful to let users designate a primary collection that a game belongs to, so that it will be shown as selected from the most sensible category and not one that happens to be first in some old song that lists letters.
On the whole this is a nice update. The most notable thing is that it matches design changes that are happening across the larger digital space. While books developed a fairly consistent design schema a long time ago, the digital sphere is still trying to do so. It still has a way to go, as seen in the choice to maintain website icons as squares (which, far as I can tell, was a change driven by Apple and their iOS choices) while something like the Steam library uses portraits.
In terms of the future of Steam, a lot of this will depend on developers using the new events system and updating their artwork. As of writing, roughly 2/3 of my games have updated art for the beta, with the rest using the capsule-style art with a blur effect to fill the extra space.
As mentioned, other parts of the client experience still use the old capsules. While it takes work to create the separate representations, having the visual differentiation is useful as far as it goes. One wonders whether a compositing system wouldn’t work better, with separate images for graphical logos and backgrounds being able to be adjusted to aspect ratio requirements at display time, with some caching for frequently composited elements. Ah well.