This game looks unbelievably good. Also, reviews are so flawed these days I hardly take them into consideration. If a game looks like I will enjoy it, like RDR, or is part of a series I have already enjoyed (NHL, Mass Effect), I'll buy it. What is so "unethical" about trying to get your game good press? Or at the very least making sure the reviewers notice some of the technical achievements.
Apparently the world in RDR is huge and very realistic, however when playing it you may be so sucked in you don't even realize that you haven't seen a loading screen in 5 hours, or that you've never heard the same dialogue line twice. Rockstar just wanted to say, hey, we did this - don't overlook that.