Got the 512 GB model to expand on the Steam Deck's admittedly limited storage. Even if you got the largest storage model of the Deck (512 GB) it can fill up quickly. Games are just bigger nowadays. I think the newest Call of Duty is like 150 gigs. Just like every storage manufacturer, they advertise the storage in "GB" instead of "GiB", so when you actually plug it into a computer you lose some space in the conversion. In this case, after you format it on the Steam Deck (ext4 I believe) you end up with 468.2 GB of usable space. Which admittedly is a tiny bit bigger than the Deck's own 465.3 GB of usable space on the 512 model. It seems like every storage mfr. has their own way of making this GB/GiB calculation, and it's just plain annoying how they always favor giving you less storage than it says on the label. It's so common now it's pretty much standard practice with them, so what can you do. But losing 9% of your storage space is never fun, so it's always worth complaining about again. The largest game I have loaded on this card is Horizon Zero Dawn Complete Edition, which is 73.48 GB. And the stories are true, it loads pretty much just as fast as the Steam Deck's own SSD. The game's intro comes with a few somewhat lengthy cutscenes, and game developers have gotten pretty good at hiding the loading screens in the background now, but still there was absolutely no wait at all between gameplay sections. In fact, I have another older game "Destroy All Humans!" (2005) on the Deck's SSD that has more hard loading screens, and it just "feels" like it takes longer to launch and load new levels than Horizon Zero Dawn on the micro SD card. HZD had a few times where it would stutter during the intro cutscenes, and drop to 20 FPS very momentarily, but for some reason this seemed to clear up after about 30 mins in, and otherwise ran at around 35-45 FPS. Definitely watchable. Gameplay was much smoother, had absolutely no stutters, and ran really consistently at around 40 FPS. Definitely playable. And not all of that may be down to the card. I'm not sure if Horizon Zero Dawn uses pre-rendered cutscenes or not (basically a video file), but it might explain the odd stuttering that only happened during cutscenes, and not during gameplay. However you would think streaming even a 4k video file should be easy, stutter-less task for this card. Another reason could be Steam's own weird download behavior: if you want to download multiple games at the same time to load your new card up, each time you click "Install" on a new game, Steam will interrupt whatever download it was currently working on and immediately start downloading the game you just clicked on, putting whatever it was downloading before into a queue. As far as I know, there's no way to just add games directly to the queue, to have them each download 1-at-a-time uninterrupted. If there is that option I haven't found it yet. (You would think this would be the default behavior anyway.) This means when I clicked on 8 different games to start downloading at the same time, each time I clicked on the next one it would pause the current download at around 1% complete, and only pick it back up again once the last one I clicked on completed. This causes pretty bad fragmentation in your game data, with the first 1% of 8 different games stored at the beginning of the card. But it could explain the rare stuttering in the intro cutscenes that somehow miraculously cleared up after a little while. Solid-state storage is supposed to have much better random IOPS read performance than HDDs, but no matter what when you've got fragmented data you're going to get slower speeds than continuous reads. FYI, you can transfer games between 2 different micro SD cards directly on the Deck. I was using a temporary 64 GB card while waiting until this one arrived, and my Windows computer couldn't read the ext4 or whatever filesystem Deck uses, and I didn't want to mess around with new drivers to get that to work. But with a few USB-C to USB-A adapters and micro SD card reader, it's easy to do on the Deck itself. It won't show up on the Deck's Storage menu of the main interface, so you have to hold the power button down and switch to Desktop mode, where you can use the standard file browser to copy things over. Keep this in mind before you start troubleshooting your wonky series of daisy-chained adapters/card readers because you think they aren't working. And make sure you format the new card first. Another FYI: I had a little scare thinking I bricked my Deck or something when I first installed this card. I made sure to completely shut down the Deck before swapping SD cards, but I think that confused the bootloader. When I turned it back on the Deck had a completely blank, black screen, and Steam didn't load. It turned out the boot order somehow got switched, and it was trying to find the Steam OS on the new microSD card instead of the Deck's SSD. To fix this is easy, while it's off hold 'Volume Down' and click the Power Button - when you hear the chime, let go of the Volume Down button, and you'll be booted into the Boot Manager. There you can fix the boot order, and I haven't had it happen again since. Just search "steam deck recovery" online for more info, Valve has great instructions.
