Have a look, download the rules, errata, and the scenarios, and have a go! Make sure you let us know if something needs fixing, or if something doesn't. If you want to praise the quality of the short fiction, you may also do so as well!
The best thing about this is, if you are like me, you have a mess of minis that you have never assembled, painted, or played with because you don't have enough to make an 'army.' Or maybe you realized that unit didn't fit in with your current list. Or the codex changed and now they suck at what you used them for. Or, maybe, you just replaced them with newer sculpts!
Now is the time to dust them off, give 'em fresh paint, and take them back into battle! the upgrades from SO:K let you break a few of the "Rules" of squad building in 40k, so you can make things that would not happen in a normal game, and really breathe new life into models that have otherwise fallen by the wayside. This is what is happening with my Khorne Bezerkers. I never followed through on making my Chaos Marine army, so the box of Zerkers had been languishing in my closet. Now they are ready to run rampant across the gaming table.
Try it out, have some fun.