I don't understand. Are you saying you bought GOW3 fully or just played the demo? You said it's a rental which would imply you're just playing the demo, but then surely you wouldnt be making such big points about the game as a whole based of a 15 minute snippet that the demo is?
I didn't want to make too much of a big deal about it because it's not like the game is an absolute fav' of mine, but i have to make the point here that to say the setting of GOW3 is worse than DMC's is just... well it's opinionated but it's just so so so ignorant. The backgrounds of GOW3 i have never seen in any other game; the sense of scale in that very first bit for example, fighting along the Titans back or fighting with the burning olympian area or behind you is great. What makes any of the DMC settings so special? They're usually the same in every game - dark long hallways of a castle or something. Only really in DMC3 did we experience anything good, like that jungle bit, but even that seemed plastered on and repetetive. GOW3's settings change continously in the full game, from the underworld to citys to more large creatures backs etc.
GOW3 has been under so much hype because it's the first GOW on PS3 and the first GOW for a few years now. The first two were the only games you would still play on the PS2 even when the 360 and ps3 were out - they wern't particularly groundbreaking (like Halo wasn't either) but like Halo their simple and efficient brilliance for what they were in their genre made them great games to play.
As i've before George you just seem to be more focused on going against the 'hype' and finding ways to hate on the popular game instead of just taking it at face value and enjoying it. I don't think it's being made as a god of a game - it's just being made out as the best possible game of it's genre, which i suppose you'd class as 3rd person hack and slash. In the same way that Uncharted 2 isnt the best game of all time, but probably the best movie-like 3rd person action adventure made so far. Anyway maybe you just didn't enjoy it and that's fair enough. Needless to say i have it and am enjoying playing it so far, although i'll agree it hasn't 'blown' me away so far but rare few games do nowadays. Have to say though, i dislike the puzzle sequences; not because they're bad, i just hate puzzles.