I have the castle and relativity issues back in the mid 1990s, they only have the cover and photo of the band with track list. This reissue by Esoteric contains a booklet with information, reading, photos and other TD memorabilia not found in other releases. Esoteric makes an effort to counter the dominance of piracy and downloading of albums by providing an extended booklet and glossy cover pages. This effort is very successful prompting purist audiophiles to buy the album again. The additional track Dolphin Smile has appeared in other compilation by TD, it only found its rightful home in this album. If you are a veteran fan whose always thirsty of TD reading which is actually rare, this is an added collection to your library. For beginners this is welcoming since it is remastered with additional track. But if tight in the budget and would be content minus the bonus track, there are many of this as used cds with affordable prizes. The TD music went to a big change after the departure of Schmoelling;gone are his ARP, Prophet 5, Emulator arsenal that produce the hard drilling TD sound of the early 80's. Enter Paul Haslinger younger,who has more of a lighter and mainstream contribution to TD (Dolphin Dance). This album is also a dress rehearsal for Franke's imminent departure from TD and a new vision for his career. Some tracks (Song of the whale) are very reminiscent of future Franke solo releases. Tracks Scuba Scuba, Ride on the Ray and the awesome Underwater twilight retain the vintage sound of TD.