@Vlad Rose: Feel free to show us how you build a 20cm x 20cm x 5cm system with an i3 and 860m for less than $550; you can only do it for less if you don't value size and custom components. So many people have made the same tired argument against the Alpha about it being over-priced, but the alternatives given are huge systems that usually don't include the cost of a Windows license or controller. If you pre-order in the US then you also get a free game (PayDay 2), possibly more through Nvidia and a $100 Dell voucher, which is nothing to sneeze at either.
Personally I'm psyched for this machine as I've been looking at building a small console-like system for a while now, and this is smaller than I could manage myself, but manages to pack a lot, at a good price. The markup to £450 in the UK is a bit steep, but compare that to the £329 PS4 and Xbox One. If you factor in a few years of Xbox Live Gold then the price is actually good indeed.
I probably will stick to the entry level model though; it only has 4gb RAM but it seems that's using a single module, so you only need to stick a matching 4gb in the other slot to double it, at which point the i3 is a decent enough processor to match the 860m, and 500gb is a good amount of storage, so there's not much need to go higher IMO as you're limited by the graphics.
In fact it's a shame the GPU isn't on a daughterboard of some kind, especially with the motherboard being bespoke anyway; with it being fixed I don't think there's much point in upgrading as you'll be better served swapping it for a new one later down the line instead when it gets a 970m or something newer. The old model should still fetch a bit of money, and with the savings on games you should still come under the total cost of an Xbox One or PS4, while jumping ahead in performance (whereas the current Alpha is only just about level).