Depends on the bitrate.

A 128kbps MP3 sounds ok on your walkman to an untrained ear, and a pretty crap on a PA. Vinyl wins.
192kbps is a little better, but probably not as good as vinyl.
320kbps is pretty much spot on. You'd struggle to hear the difference between that and a WAV, even on a PA. Much better than vinyl.

All depends on the encoding rate.