First off, I don't think that any previous generation GPU architecture will compete with Maxwell. Also, I don't recommend anyone just rush out and buy one when they are released. It's not that I think the money will be wasted, but that this is a new approach and there is no telling how it will really play out. Primarily the design is intended (rumored) to correct for energy and heat issues that have plagued earlier designs. However, Nvidia is also attempting to decrease dependency on the CPU, and they are doing that by including a CPU on the card (alongside the GPU). Add to that the high cost of memory on a card that is intended to increase GPU memory (6-8GB on even mobile platforms) and it sounds like Nvidia might be setting themselves up for a face palm moment. How all of that will mix with the attempt to utilize system memory is anyone's guess, until we actually see the goods. You can bet Maxwell will not be cheap.
I can't wait to see the real deal, but I'm not looking forward to the inevitable sticker shock.