The new player offers GPU and DSP decoding on select platforms. There's support for new codecs, demuxers and muxers, Lua extensions and Lua content extensions and much much more.
There's a lot in this upgrade, but one thing that isn't in there and is SHOUTcast support. According to VideoLAN, AOL Corporation told them that in order to continue using SHOUTcast, they would need to relicense the media player as closed-source and include AOL's adware software. You can learn about that kerfuffle here.