You would think it had a synth for its piano layout on the pads, but unfortunately you gotta build your own synth with the Pitch Function (Which is fun to do IMO).

If you sample one piano key on the 505 and send it through the Pitch Func, then yeah, you can play it like a keyboard. You can build a pattern and record the keys on top too, but limitations with the polyphony can mute notes.