I have some questions on this album.

1.Will I like this album if I liked Ys Perfect Collection?
2.How does this Perfect Collection compare to the others?
3.Is this album rare?
4.Is this album good trade bait?

1. Depends what you're looking for...It's melodically pleasing, but the actual arranging isn't so great (outside of a few tracks) and the tracks are dreadfully short. I heard it before most of the other main Ys albums (I literally got it a day before my package with the first two Ys Perfect Collections showed up) and I still listen to it today (I listened to it at work today, in fact...Scary).
2. Not as good as I and IV, MAYBE better than 2 (it has more tracks I revere than 2, but 2 flows better and is easier to listen through). Of course, Ys Oath of Felghana complicates things, since it's a complete remake of Ys 3 and I'd probably rank it as being tied with the Ys IV Perfect Collections (and significantly better than Ys 3 Perfect Collection). And there's also Ys 3's Turbo Duo redbook.
3. Yes, but it still pops up and doesn't go for insane prices.
4. Dunno.

I wouldn't make it a point to sell your life for it, but if you like Falcom's music and find it for a good price, get it. It's flawed, but fun.

1. They're really not that similar.  The first Ys Perfect Collection was one disc full of rocking Ryo Yonemitsu arrangements and one disc of solid re-arranges.  Ys III Perfect Collection is much more uneven.  Honestly, I would recommend trying the Ys: The Oath in Felghana OST before you think about Ys III Perfect Collection.  The arrangements are FAR superior on Felghana.

2. In my mind, it's at the bottom.  This and Perfect Collection Sorcerian Vol. 2 are probably the Perfect Collections I listen to the least.

3. Rare?  The original pressing isn't all that common, but it shows up from time to time.  The Oath in Felghana LE game from Falcom came with 8 Ys III CDs, including this album, so at this point, it should not be hard to find if you're interested.

4. Trade bait?  I'm not sure.  Most people who are into Falcom music probably already have it.

I found it for a really good price and it is the limited edition with art on the discs. I'm not really expecting great things from it but I mostly want it so I can put it up for sale/trade.

1. The arrangements are not that great compared to Ys I and II Perfect Collections.
2. Probably considered the "worst" of Perfect Collections in terms of arrangement.  Ys Oath of Felghana is a better Perfect Collection of Ys III.
3. Not terribly.  It still shows up on Japanese auctions and ebay, so it's not too hard to find.
4. Not really.  Only good for Ys completionists.  The dollar value on it is generally $25-$35.