Well, while its a lot like BGG, I find it much better for reviews and recording what people like and have played. I know for me, I've found games that I would never have looked at because, while they're popular and talked about a lot on BGG, you just need to look for them. I found out about Dominion and Carcassonne, for instance, on this place. I also like how you can see the average ratings for the game from the reviewers and such. Sure, BGG has it - but those numbers are ALWAYS so skewered and wrong that I don't pay attention to them for the most part.
So, its got its niche. Does it replace BGG? Nope, I don't think so. But, I think it works well hand-in-hand with BGG as an outside source. What I'd think would be great is if we could make Mage Wars the top game on that site - so people can see how great the game is going to be.