Nice, rock solid metal case (only sides are plastic).
Keep in mind that keys on SL73 Studio feels heavier than keys of classical piano, the action is viscous and if you want a faster and "lighter" keys it would be better to consider picking the SL73 Grand edition (or SL88). Otherwise, you will get a muscle training station :) I got used to it after tweaking the velocity curve, but obviously, the physical key return is still slow so it's not the best keyboard for the fast rhythmical same-key patterns.
What's good about the keys – their range of sensitivity is wide, I barely can hit the 127 velocity. What's strange is the aftertouch resolution which is very low, but I think that's not critical as it's rare to be used on the weighted keys. Quality of keyboard is good and I love the joysticks.
It works out of the box with Linux! It can send the program change MIDI events after configuring its program presets, so, I think, it's a nice keyboard to be used with Pianoteq installed on Raspberry Pi or similar ARM board.
Keyboard works well being powered from my PC's USB, I didn't notice any problems, so, no need to plug the dedicated power supply.
Conclusion: a rock solid, heavy, weighted keyboard in a metal case, probably, the best you can find for such low price. Want faster keys? Take a look at SL73 Grand.