I had a good feeling the review scores would be decent - the devs were obviously proud of their work and weren't afraid to show off the game in pretty hefty chunks. They're actually ending up better than I expected, and needless to say that I'm in on day one (PC version, Green Man Gaming FTW).
The most shocking thing must be that a heavily hyped feature (the Nemesis system) actually managed to live up to the hype. I was expecting a solid action game with a Nemesis system that showed hints of brilliance but contained enough flaws/cracks to make you go 'yeah, this is OK, but it's still half-baked'. The fact that reviewers are pretty much universally praising the execution of Nemesis is very good for the game, and hopefully very good for our chances of getting more high quality emergent systems in future games. High quality next-gen graphics are nice, but the real promise of next-gen is making games more dynamic and less predictable, and it looks like Shadow of Mordor is leading the way.