First of all, Swing has good build quality. It's sturdy. Knobs and buttons are fine. Nothing to complain here.
It's quite easy to use. My only complaint is the sequencer which is next to useless. Because we can't see which step is edited, counting the number of steps recorded into the sequencer is needed. Editing such a sequence is not intuitive and can be messy because many functionalities are not indicated in any way. Was the last step finally removed so I can stop pushing those buttons? It's a guessing game.
Besides that, everything else is good. Keybed is fine. Nothing amazing, but it feels better than a typical cheap synth keyboard.
Overall, 4/5 because of the sequencer.