Honestly, there's no game like it. It's quite possibly the greatest game ever made, even with it's (many, though mostly very minor) issues it still has. If you like action RPGs even a little bit, you should enjoy this. The characters, graphics, and voice acting are all the best in the industry (or at least extremely close to it) even after 4 years. The only complaint I'd have really is about the traffic/crowd AI. It's pretty horrible. It's serviceable enough, but it's some of the worst of any open-world game I've ever played with vehicles in it, including some indie games. I'm making it out to sound worse than it is, though. It's really not that bad, it just could be a lot better. This definitely ain't no GTA, and that's fine, (I guess). Overall, I'd give the game a solid 8 or 9 out of 10 (let's just say 8.5/10), and I'll just round that up to be 5 stars for GOG's ratings system.
I've played this on basically every platform available now... The game has it's flaws, as all Bethesda games do, but it's one of the best games of all-time in my opinion... I'm not sure if I'll actually play it again any time soon, but figured I might as well grab it while it's cheap... Love that we can disable auto-updates and rollback to old versions... If I do play again, it will definitely be this version...
