Man, what it is with some of you guys? Why all the attacks? Some of the stuff you said could actually have been constructive feedback. So he's trying to make some money out of the game he developed, big deal.
I'm not really looking into playing online games, but most of what has been said is also true for me.
I do enjoy "alternate universes" in the sense that you can immerse yourself in another world with a background and a specific culture or whatever. I just had a (quick) look at your guide, and there's no mention of anything of the like, so for me, it's a turnoff.
I also have to agree on the sprites&background. While the different backgrounds do seem to provide some variety, for me (and like Caliber9 said), there doesn't seem to be any coherence between them. For someone who likes a well defined game theme, this isn't so good.
While I understand and see the viability of the pay-for-more model, it really irks me, maybe because I like to see things as black & white (pay or free) and this is in-between. This may also come from the fact that a lot of times the game seems free until you play awhile and then realize you're limited unless you pay (which means developers hide it). You're upfront with it, so it's cool
All this said, even though there are different styles for the art, each of them seems to be of pretty good quality
I'm not an artist, but I like it.