My Steam Deck experience has been very positive, it’s a great way to play games away from the desk. For me the controls are great, and game compatibility continues to surprise me.
I would say the only problem with the Deck is the size - it’s big. When I got mine it seemed a lot bigger than I realised, and that was after watching/reading a lot of reviews. Depending on your hands the size might be an issue. If you know anyone else with a Steam Deck I would recommend trying it out for size before buying.
The aftermarket shells can be very good quality these days, if the original shell is badly scratched up I would just replace it.