I have steam deck 64GB + 200GB mSD + cheap antiglare from amazon. Very happy with it:
Around the house, I stream (instead of local play), from desktop (3090 + 5950) it works very well.
emulators (this is a major 2nd benefit,
https://www.emudeck.com/) also works very well.
Streaming the LCD to samsung 8K TV (that is driven by the 3090 normally) using steamlink also works very well.
2nd player on Bluetooth while streaming also works well.
notice the trend?
streaming emulated NES/SNES to the 8K, playing 2 players with my kid.... priceless. And it's only 2 minutes to fire up. and literally 45 minutes to setup when I got the deck. Great ROI on your setup time investment.
For me, SteamDeck is a new frontier: it enables new scenarios with polish that windows simply can't touch. It just works. This review captures it well, but maybe in more objective manner, if you're still reading, it's clear I am a fan of the deck.
I am at a point I just want my portables: phone, steam deck, and laptop to just work. Even if it means the experience is little more limited. Happy to tinker at my desktop, but don't want to do every day, at the bus, or the train, etc.
I am sure Tom's reader can fix any issues on Ally with Windows, with the help of google and reddit, and gobs of free time, only to do all over again after an update or two. An obscure Z1 processor that ASUS / AMD makes very little money on? that's a recipe for engineered obsolesce.
Valve on the other hand, wants to sell their ecosystem, even if that means taking a loss on hardware.
With steam deck, someone else is fixing these issues. For free, every time... all for ~ $450 and very little time on your end.