I got my four-CD box set of the Suikoden II OST a couple of days ago and I'd have to say it's not as good as the first OST, but if you really liked the Suikoden I OST then it is definitely a worthy purchase. The OST is very good but first let me tell you there are many tracks you'll want to skip, and there are many different versions of some tracks in which the original track wasn't even that good, let alone the different versions. I wish they would have shortened the OST to three CDs instead of four. Also, unlike the Grandia OST, the great music is spread out in each of the two-CD volumes, leaving the people who want to listen to the best of the music on the OST having to buy two expensive double CDs.
Now the good stuff about the OST: there are many versions of Suikoden I's Main Theme which are very pleasing to the ear, and there's other music from the first game (such as some of the town themes, battle themes, Suikoden I remixed tracks, etc.). Some sound very like their originals while others are remixed.
The sound quality isn't as good as in the first game, mostly because they made the game twice as long as the first (leaving less work space for the score). The quality still sounds very good, just not as good as the first. The high points in my opinion are the vocal tracks. The opening track is very powerful as was Suikoden I's, and includes a latin chorus this time, while most of the other vocal tracks in the game are surprisingly enough sung in Italian. There is a very beautiful, however more relaxed version of Suikoden's main theme song sung in Italian, and I just love the end song. It is sung in Italian and is a very moving and beautiful track, one of the best on the OST, even though it is quite short.
If you don't have 55 bucks to spend on the four-CD boxed set I'd hold off, but if you have to chose between the Vol. 1 OST or the Vol.2 OST, I'd go with the 2nd Volume - it arguably has most of the best tracks in the OST. In conclusion, Suikoden II's OST doesn't meet the standards left by Suikoden I's OST (pretty big shoes to fill), but it is still a great achievement. If you have the cash to spend and liked Suikoden I's OST, then by all means, buy Suikoden II's OST. Others might want to hold off right now and wait until they play the game or sample some of the music.