Assuming you mean Steam Deck and not one of the others. I don't like using it, but wife wanted it and I don't get the appeal of it. It's harder to work with than a laptop/pc, and isn't as simple as consoles. It's not that portable (much larger and heavier than a Switch). I generally like tinkering, but it pissed me off setting it up.
I guess one thing that annoyed me was that I didn't realize the eMMC version means you had to remove the drive completely to replace. It's not an extra drive slot. Which means you have to reinstall the Steam OS on it after you replace the m.2 module completely. So if you're going to go that route, don't set anything up like I did, because you're going to have to do it again after you swap out the drive. Also, don't charge it to full if you're going to to swap out the drive.
I also copied the backup files from the 106 GB Baldur's Gate 3 install on an SD card, only to realize that it needs the Linux version or whatever, so I just ended up downloading it again.
All in all, a lot of time wasted, half my own fault and half wife was bugging me about it so I didn't read up on things first (even though she said afterwards that she meant for me to do it at my leisure and not the day she put it on my desk with puppy-dog eyes).
In the short time I used it, I also had a hard time figuring out how to install something natively on it instead of streaming it from my PC, if I was logged into Steam on my PC. And I had issues with the trackpad being too sensitive, which further annoyed me.