The soundtrack of Hotline Miami is fantastic, matching perfectly to the quick and deadly levels. They have become game music classics. I will very much recommend these.
But, all tracks except for “Vengeance” are already included in the main game. Just have a look in the game folder! They are encoded as Ogg Vorbis, which might be a bit less of a quality, but frankly, for this style of music it’s mostly undiscernable.
If the soundtrack GOG offers would provide FLAC versions in best quality, a four- or five-star review would seem appropriate. But with just about no advantage and a price HIGHER than the full game including all tracks (except one), this is only for enthusiasts and collectors (with too much money at hand).