I like the artwork on the pro. I actively don't like the hammer on the premium but I do like the RGB lights and the proper lock bar and service rails. But I didn't like them enough to justify it $ wise. For some sterns premium is the way to go (ac/dc) but for metallica the difference is small.
Whatever version it is a great game and you will not be disappointed. Great rule set and layout and if you like the band it will be a favourite.