There isn’t much to preview with that soundtrack unless you’ve never played a Sonic the Hedgehog game in your life. It sounds just like the in-game music to the various Sonic games, but the quality is better than most of the Sonic audio rips floating around on the Internet. Of course, that only applies to the tracks that have never seen an official soundtrack release (Sonic, Sonic 2, Sonic 3, and Sonic & Knuckles).
So, unless you’re a completist or a huge Sonic fan, I would suggest that you don’t purchase the soundtrack because it’s basically just a "sampler"/"best of" soundtrack. As it’s also out of print, I’m guessing you’re going to have to pay at least a little more than what it originally cost, too.