Yeah, AC4's OST was only 2 discs, when I saw the pre-order was up for AC5 I couldn't believe there were gonna be 4 CDs, but they were each about an hour long, so there's no way they could have made it a 3 CD package. Even in the linear notes they said this is probably the biggest package for a game OST ever. The price's sweet too. I picked up the MGS3 OST (2 discs) at the same time, and that one was only 800 yen cheaper than AC5's 4 discs. I've been listening to AC5 OST almost nonstop, MGS3 OST didn't get much playtime since I hated the 007 wannabe OP and the overall BGM just isn't as enjoyable as the music from the first 2 games.
"The Unsung War" is awesome in Latin. Kind of sucks when you realize they're just repeating the same 3 verses over and over though.