Good mixer, I've had one since 2009 and love it. It's amazing for scratching, many of the world's best DJs prefer Rane faders. The downside to the older 57 is that it only works with Scratch Live and not the newer Serato software (Serato DJ). You can chain a SL box to the mixer and use it for Serato DJ though.
If you're buying new I'd suggest going with a 61 or 62 instead. The new version of the 57 was put out mostly to keep existing/nostalgic/change-hating customers happy imo.