I really don't see this as being useful for anyone outside of hard archivest. The bitrates are pretty trash. I guess if you just a setup with an incredible amount of music no matter what, this is for you. IMHO the meta data is worth more than these lower quality sound files although we have meta data for what's out there now.
Outside of that here is what and how they are going to release. I'm guessing this drop was their "popular" track drop. From their site:
For popularity>0, we got close to all tracks on the platform. The quality is the original OGG Vorbis at 160kbit/s. Metadata was added without reencoding the audio (and an archive of diff files is available to reconstruct the original files from Spotify, as well as a metadata file with original hashes and checksums).
For popularity=0, we got files representing about half the number of listens (either original or a copy with the same ISRC). The audio is reencoded to OGG Opus at 75kbit/s — sounding the same to most people, but noticeable to an expert.