It’s a handheld that can play basically any game through the previous generation and even some current AAA titles. If you have a steam library already, most of your games are suddenly playable on the go. The hardware is open with spare parts easily obtainable so that you can repair it yourself if you drop it. Valve is very engaged with maintaining and updating the software to be an enjoyable experience whether you prefer console or PC. Because it is subsidized by software sales the hardware costs less and drove down prices in the industry for competing products. When my 10-year-old motherboard gave out in my desktop, I was able to use the Steam Deck as my primary PC for a month while I took my time putting together a new computer. Also, you are very correct that it has had a meaningful impact on Linux gaming.
In my opinion, there’s a lot to like.
Law protects capital.