I own a copy of this particular doujn. Is it worth checking each other individual book by the same artist? Do they have anything more to offer or are they basically the same story and graphics?
I must add, thanks a lot for scanning this little wonder! Royal Moon really draws the best gardevoir and it's a shame his works werent't featured more promenently on this site.
@San Liberty- I own all but one of the original works included in this compilation. One major difference from this to the individual books is that this only includes Shirane Shiratsuki's own works. The books they are taken from were usually released with at least a few pages of guest works, which are not included here. Perhaps the most glaring example of this is Syncro*Meditation (which I unfortunately have not been able to find a copy of anywhere) which was more of a collaborative work in the original, but here is only re-printed with Shirane Shiratsuki's pages. Another good example is SweetknighT, which is cut off about halfway through here, because the second half of the original was done by Neichi.
Additionally, the cover art is obviously in glossy full-color on the originals , but in one particular case (Egg Royale) there are a few pages of full-color work that are reproduced here in simple grayscale.
Personally I could take or leave the full-color thing, and if you only care about Shirane Shiratsuki's stuff to the exclusion of other well-known artists doing Gardevoir stuff, then I would say that sure- the originals may not be worth seeking out, but personally I think you're missing a lot in some cases. What you can do is check here on e-hentai- I've actually just scanned and uploaded all of the books included in this compilation (except for Synchro*Meditation, which you can still find here by searching) and you can see for yourself what you might be missing out on with each of them.