well not many issues, but more specifically 3 MAJOR issues that bring the product down....
incredibly large size, no OLED and lack of battery life.
the damn thing is about as large as a Wii U gamepad, when you're trying to sell a handheld you need it to be actually portable and the Steam Deck is barely teetering the line between actually portable just a house device
the Switch OLED has pretty much set the standard for handheld screens, you need to have your screen be vibrant the same way the Vita 1000 or Switch OLED are vibrant. Many people complain about how awful the Deck's screen looks, Valve needs to fix that asap
and the battery life is real important on these things, if they cant offer a replacement or even a model with better battery it's not good
the software and compatibility are fine, i've tested steam on linux myself and besides destiny 2 everything ran. It's the fucking hardware that is lacking. people want a smaller handheld
they need to make a deck lite that addresses at least the battery life and size. The DS didn't take off until Nintendo made a lite model 2 years later, i think Valve can take notes