It's an OEM-only, 2003 R2 server-based, with all the fancy services stripped out, intended to be so simple that "mom can use it". This means that it's not going to be a DC, and it also means that most "enthusiasts" will not be using this product -- you just can't buy it by itself, and need to buy an integrated box to get it. Real enthusiasts would be more inclined towards solution that they can be much more selective about, and mix & match and customize in implementation.
This is Microsoft's answer to Linux as provided on several commercial NAS boxes. I believe that it should compare well with them as they currently stand from a performance standpoint, and ease of use and maintenance, but probably not in price. Moreover, there are some signs that ultimate performance might be somewhat compromised in the name of convenience and ease of management. (This might to some degree be mitigated by faster future HD's, e.g. the upcoming Hitachi 1 TB ones.)
Assuming that MS doesn't fully cripple it for this role, I think that a Vista-based home-brew solution could actually perform better and be easier to obtain for the real enthusiasts. Of course, such enthusiasts also have Linux and older Windows OSs to choose from, as per their wishes and needs.
This product seems like a good one from the ease of setup perspective, and there's a good market for that, but it's not exactly the "enthusiast" market, as the article says, this isn't designed to make a geek happy.
So my answer is an unqualified "no", I'm not going to be buying a custom box to get this OS to do stuff that I can already easily do with several other means, and probably out-perform in the process.